I found it an odd mix of her usual 'middle-class angst' themes and, obviously, more unusual themes and settings. I didn't quite know what to make of it, TBH. The writing style and narrator's voice seemed very matter-of-fact and detached; I guess that was meant to reflect the narrator's state of mind but it was hard to sympathise or even, sometimes, to grasp what was going on.
Yes to the rather annoying 'middle class angst' stuff. To be honest, I thought it was far more about that and the whole 'pity me but I want it all' stuff than it was a post-apocalyptic novel and that, in a way, the post-apocalyptic stuff was just her attempt to make it appear to be a better book than it actually was.
She didn't really develop the 'post-apocalyptic world' or the 'disaster' in sufficient detail to make it meaningful - it was just a kind of veneer to try and lift a pretty bad 'female misery' novel into something else, I thought. It was too simplistically realised and too derivative to matter much imho.