In one of Terry Pratchett's books, a member of a clown family runs away to join a band of travelling accountants. Dunthorne's book contains a similar reverse rebellion when sensible Kate flees her boring life in an alternative community to explore what she hopes will be the dark underbelly of suburban life with the family of her boyfriend, Geraint.
In reality, the darkness was in the community all along. It is an edifice seemingly built on the vanity of her father, Don, and has some serious structural problems. In flashbacks that feature alongside the current narrative, it becomes clear that the "community" is really just Don and his university friends drifting into adulthood, never quite having parted, with student frictions and rivalries fossilised along the way (including those with their former landlord, Patrick, who joined the group and has been installed in his own accommodation, a geodesic dome which he suspects - rightly - was designed by Don to isolate him. Dunthorne deploys some cruel insights in this book, none more so that when he remarks - in connection with the construction of this dome - that the only difference between something done from love and something done from spite is that the latter will adhere better to a timetable.)
Something I particularly enjoyed in this book is Dunthorne's portrayal of his characters, which he succeeds in making at the same time sympathetic and deeply unlikeable, especially Albert, Kate's Bart Simpsonish brother. He is though a Bart with a steely edge. When Kate betrays him by leaving the community, and him, to revise for her A-levels with Geraint he becomes seriously weird, convinced that the world will soon end, and plots revenge by killing her favourite goat and serving it to her (Kate is a vegetarian).
Kate is also portrayed well. At the start I felt some sympathy for her - a normal person in a weird setting, perhaps echoing Saffy in "Absolutely Fabulous" - but she also has a ruthless streak, intending to abandon Geraint once she gets to Cambridge and trying (and failing) to seduce his father.
Re-reading my last few sentences I'm worried that I may have made this book seem a lot darker than it really is. It is for the most part very funny - for a given value of "funny": few laugh out loud moments but plenty of grins - and fun to read. In the end, everyone survives (though there are a couple of close shaves) but it's clear there will be change (not before time) at the community.
Finally, some of the other reviews of this book suggest that the author seeks to shock. I really don't think that's the case. With two possible exceptions, nothing especially "shocking" happens (at least not in the view of this this boring middle aged male reviewer) - especially, perhaps, given the self consciously "alternative" lifestyle of some of the characters.
Of the two possible exceptions, one is a potentially violent incident, one of the close shaves I refer to above, which arises very much out of the development of one of the characters. I would describe it as scary rather than shocking. The other is the shower, shared by Kate and her brother at the start. But that, too, arises from solid plotting and character: the Community has limited hot water, it's something they have done since childhood, and Kate (already toying with her rebellion into "normality") wants it to stop. Indeed, it's the way that Dunthorne first introduces this desire on her part. It isn't shocking, and it isn't designed to shock.
I may have laboured this last point a bit, but I think that those suggestions are really misleading. This isn't always a "nice" book, but it isn't trying to be "nasty".