Considering the book is about "crap towns" in the UK, I imagine it could be a very different demographic than the one you're thinking of

hmm, maybe. In the U.S you have often the person who moved from a 'crap' town to some place they consider great, who gets really emotional about the crappiness they escaped to be able to think freely and the like. And often these people are the ones I would think of as customers for a book like this, and if their new town isn't in the book they certainly won't be offended.