At one point, Fay Weldon says: "Of course what you want is universal admiration all the time. Doesn't everybody?" So it must have been particularly galling when her new book Chalcot Crescent, was rejected by her publisher, the first time this has ever happened in a career spanning five decades. "I was outraged!" She laughs, eyes disappearing into cheeks, her shoulders becoming even more rounded. "But I take responsibility for it, I don't blame them. It was so different from what they were expecting."

Within four hours somebody else had bought it, which is what brings me to her kitchen table in her lovely stone house in Dorset, where she lives in apparent bliss with her third husband, an Aga, a library and apple trees. She must have bashed out the book at speed, even by her own prolific standards, because it is set in the aftermath of the "Shock of 2008, the Crunch of 2009-11", which is followed, according to Weldon's prophecy, by the Recovery of 2012 and then the Bite: protectionism, rationing, power cuts, a surveillance society. "What struck me is that it has changed so fast," she says. "That's why the book is only set four years in the future rather than 20 years, because it seems to be a very possible idea."

The recession is "dreadful, of course it is," she says, but Weldon, best known for The Life and Loves of a She-devil, also believes it is a chance to remake society, particularly in a way that will benefit women. "Women exhausting themselves with useless jobs instead of looking after children couldn't be sustained," she says. It sounds as if she thinks women should stay at home. "No! I'm sure there are lots of women who want to stay at home and look after their children, but I don't want to force women back into homes. Homes are boring, looking after children is dull. What I mean is, if what was made by a society was needed by a society then everyone should work a lot less hard. I certainly don't think we should go back to the old days, because the old days were a nightmare. But it's nightmarish now for women, who are just tired. They have to do too much and wages have been kept so low, because women joined the labour market. As it has turned out, the whole relationship between men, women and children has tilted, to the disadvantage of women." What does she think the solution is? "The entire collapse of society and remake it in a more radical and humane way. A change has been forced upon us and that may be no bad thing."

Weldon has been doing interviews all day to promote her book and looks a little weary, even if she's trying not to show it. I ask her how much of what she tells journalists is true and she laughs and says, "Ooh, about 60%". She smiles and giggles her way through every sentence so that everything she says comes out sugar-coated. On having children: "[They] are a terrible bind, I wouldn't argue with that at all. I've brought up my children all wrong, but there's not a mother in the world who doesn't feel that." Hee hee. On women getting too ahead of themselves: "I think five or 10 years ago, young women were so rude to young men that they fled in terror. But that seems to be getting better." Ha ha.

Weldon is 78, but seems so girlish (it's the round face and the giggling). She was never a typical feminist. She took her husband's surname, and she has had a few nips and tucks. She was vilified for her assertion in an interview in 1998 that being raped wasn't the worst thing that could happen to a woman, and a few years ago she complained that feminism had undermined men too much. In her book What Makes Women Happy she advised faking orgasms. Did she feel part of the feminist movement? "Inevitably, but I never wrote propaganda because it all seemed so evident. It became obvious that you had to be a feminist because it was such a ridiculous state of affairs." Her contemporaries, she says, "usually come round to my way of thinking in the end. I'm probably the one, the only feminist there is and the others are all out of step."

She recently said the problem with most feminists was that they were so boring. "They're getting a bit better, because at least they are more interested in women in other lands," she says. "In the last five years, it has been so inward-looking – they have been worried about pay gaps, worried about the minutiae of things – that it got up its own arse. Now, [the feminist movement is] looking outside – you see what's happening to women in Afghanistan and you see the necessity of fighting back. You need to work in those areas. It is too easy for women [in the west] to see themselves as victims and oppressed by men. I think one has to be more rational."

But what about the different pressures on young women now – young men growing up on misogynistic magazines, internet porn and lap-dancing clubs appearing on high streets? "Yes, but the women are doing it," says Weldon. "They don't have to. They can always get a job in the frozen chicken factory. Selling your body is no awful," She has a habit of not finishing sentences. "It's not any big deal. Good for you while you have it, you won't be able to do it for long and then you can get a job as a typist or whatever." Again, she is laughing but I don't think she's being ironic.

Weldon is talking, partly, from experience, but she says: "Oh I'm not going to talk about all that." In her autobiography, Auto da Fay, she wrote about how her first husband, who didn't want to have sex with her but tried to pimp her out to his friends, suggested she get a job as a hostess in a Soho clip joint. She is cagey about the details – she even writes about herself in the third person to gain some distance – but as far as I can tell, it was "the dangling of the legs from barstools, the semi-baring of the bosom, the flirting and the dancing". But when it came to sex, she writes, "Mrs Bateman [Weldon] would rather give it away for free than feel indebted to those who paid her." "Sell your body," she writes, "and you sell your soul." Which isn't really what she is saying today, but then Weldon is nothing if not contrary.

'I really liked [working as a hostess]," she says with a laugh. "I should say, 'It was shocking, it was traumatic, it was terrible.' Oh no, I was a perfectly willing participant." Who knows if she means it. But did she never feel guilty that she was part of an industry that objectifies and exploits women (oh dear, I sound terribly serious and here she is giggling away). "No, I'm sorry, I'm afraid I didn't. It's not the most awful thing that ever happened. It's just people without the grace of god, just animal behaviour. It's sort of grisly. People are sexually-motivated and like to be turned on so let them be turned on. I think it probably is [damaging] if you take it to extremes, but it's not in itself … It's a gratification of a Darwinian instinct. I wouldn't ban it, because it would just go underground."

When Weldon was 22, she became pregnant by the doorman of a nightclub, but life as a single mother was hard, so when Ronald Bateman, a headmaster 25 years her senior, asked her to marry him she agreed. Then, bored, she left him, found a successful job in advertising (she's credited with the slogan "Go to work on an egg") and married Ronald Weldon, a jazz musician. They were together for 30 years and had three boys. During their marriage, her husband encouraged them both to see therapists, until he changed his and started going to an astrological therapist, who told him that his and Weldon's star signs were incompatible. He left her for the therapist, whose star sign presumably was, and died of a heart attack on the day their divorce was finalised in 1994.

Her third husband, Nick Fox, is a poet who she met in the early 80s when he was running a book shop and is now her manager/editor/accountant/lover (me: is sex still a big part of your life? Weldon: "Well, I think, yes, it's part of being alive isn't it? But you're not going to get me on that one. It's distasteful to the young.") Why does she like marriage so much? "I was brought up in a world where to be married was the only thing a girl wanted. Also, I think the outside world is quite dangerous and frightening and it takes two of you to face it. You need someone there to be on your side."

The mistake young women make, she says, is leaving it too late to get married and have children. "It's better to get it out of the way. Getting married young is a good idea and having babies and then getting divorced." Divorce is inevitable? "You're less likely to get divorced if you do it sensibly, but then you'd just die of boredom. So you should do it rashly."

She isn't a flirt, she insists – though there is something sexy in her plumpness and the glint of her eye – but men like her, she thinks, because "you stop being judgmental and they're so relieved you're not finding fault with them and making them feel bad. I think I was always good with relationships, they just weren't very good with me." She laughs. "But I don't regret anything because it's all good copy."

Weldon says she thinks people's lives, particularly women's, "are only interesting for the first part while they're trying to find themselves". But she hasn't lost her capacity to, if not shock, then certainly cause ripples of bemusement. When she was in her late 60s, she found God and was baptised. She was an atheist, but now she goes to church every week. "I think it's important to go and sit and think about something other than yourself, pray for the sick, consider the dead," she says.

She has already finished her next novel, her 30th. "I'm exhausted now. I don't think I'll be able to do one for quite a bit because it does take it out of you." I wonder if she feels she has never been given the respect she thinks she deserves, and has been dismissed as a "women's writer". "Of course, and the covers have done [my books] no favours at all." (She thinks they make them look like chick lit.) In 1979, her novel Praxis was shortlisted for the Booker prize – has she wanted to win prizes? "My sentences are too short, and if you want to win prizes, and be taken seriously as a literary writer, you have to take out all the jokes. I've judged enough prizes in my time to know the most boring book wins. And that's not the book you want to write." The literary world perhaps hasn't forgiven her for taking money from the jewellery company Bulgari to write a "product placement" novel, The Bulgari Connection, not that she appears to care.

Weldon bustles about her kitchen, grandmotherly, bringing coffee and cakes. We chat about the break-up of Katie Price's marriage (Weldon reads the Daily Mail website every day for her fix of celebrity gossip) and the impending apocalypse – "although I probably won't be around" for it, she says.

Weldon says her local doctor keeps trying to give her a pneumonia jab, but she refuses. "I don't understand this obsession with longevity, this living until you're 100 and being incapacitated. I've had a good life, I've done what I wanted. Now I'll take my chances."

Chalcot Crescent is published by Corvus (£16.99)