Had a conversation with my editor today which was good. I'd sent her a whole load of illustrations (photos and cartoons) that I'd ideally like to use for the book and she's very happy with them, so at least I know I'm going down the right direction. There's still quite a few to source but I'm at least three quarters of the way there.
She was also discussing the cover design with her designers, and I've been asked to think about possible ideas too. It's quite scary thinking what could possibly sum up the whole book, despite the saying you can and often do judge a book by its cover. I'm sure the designers will come up with some good alternatives.