Last July, Blur played the biggest shows in their history over two weekend nights at Wembley Stadium. For Damon Albarn, Graham Coxon, Alex James and Dave Rowntree, it was a signal moment in an objectively great band’s history. They weren’t just huge gigs, but emotional, powerful concerts, with Albarn in tears on stage at one point.

I was surprised, both while attending one of the concerts and watching the accompanying documentary film To the End, at the band’s awe, almost surprise, that they were playing Wembley. You are, you want to remind them, one of the best and most beloved bands in Britain. In Over the Rainbow, his memoir of Blur’s comeback year, Alex James is either naive or a little disingenuous when he ponders if they would be able to fill the national stadium: “Would anyone,” he wonders, “really be persuaded to go to downtown Brent on a Saturday night in summertime?”

But this is less the story of a rock band reconvening for one final(ish) weekend of triumph than a 180-page insight into the joyfully chaotic life of Blur’s food-obsessed bassist. James has written two other memoirs: the first, Bit of a Blur, told the raucous story of 90s excess, the second, All Cheeses Great and Small: A Life Less Blurry, the less-raucous tale of swapping life in London for a rambling farm in the Cotswolds. Over the Rainbow is a mixture of these two strands: the story of trying to balance the demands of running a farm, and the festival that takes place there, with a return to stadium rock’s frontline. The dietary excess of living on a “food machine” is a major thread of the first half of the book, as he desperately tries to lose enough weight to fit into his “Britpop trousers” in time for the shows. James – a man who once claimed he spent £1m on champagne and cocaine in the 90s – notes the irony of needing the discipline of a rock band to save him from the excesses of the farming lifestyle.

He is an underrated musician, but don’t expect tracts on the merits of the Fender Precision bass: his passions are of the edible sort. There’s probably more in Over the Rainbow on the merits of broth, crisps, cheese on toast and cider. And there’s less than you might expect on the relationships between the members of the band.

That’s a shame because, as interesting as the story of the English sparkling wine James has sourced for his festival is, it wouldn’t hurt to have a bit more on the mechanics of the reunion. There are some touching moments in To the End, when relations between James and Albarn tentatively thaw over a pint near Albarn’s home studio in south Devon. Here, the only hint at complex dynamics comes at a show in Mexico City, during which Albarn won’t even make eye contact with his bass player. James is crestfallen until he discovers that the singer is actually just trying hard to fend off a bout of food poisoning.

James’s most endearing quality is perhaps an inability to take himself too seriously. He is man fully aware of the pleasures of a life lived ridiculously. When the reuniting members of Blur share what musical projects they’ve been working on, he’s quick to tell them he’s been busy trying to create a giant Frazzle, in the hope that an outsize version of the bacon-flavoured crisp might replace disposable plates and cutlery at his festival. He embodies a sort of joie de vivre-infused chaos and seems to spend money like a drunken sailor. At one point, while waiting for payments from Blur and the festival to kick in, he is given some money by his mother-in-law and immediately takes his wife and five children to Mayfair to have lunch at Scott’s, replete with beluga caviar for the kids and Dom Pérignon.

Even if some of his storytelling tics are grating (there are a lot of first-name-only references to people we don’t know), James is an entertaining narrator. You might not learn much about rock’n’roll while reading Over the Rainbow, but – like the author – you’ll probably have a fine old time while doing so.

• Over the Rainbow: Tales from an Unexpected Year by Alex James is published by Particular (£18.99). To support the Guardian and the Observer buy a copy at guardianbookshop.com. Delivery charges may apply.