I thought I would post this here as I know some people are getting the Revell kit (I have 2 and am itching to get another!).
http://www.amazon.co.uk/Routemaster-Bus ... k_h_b_cs_1
I saw this book mentioned on another site and the person said it was very helpful for his build.
I got my copy and I think it is great value. Lots of colour pictures of busses in service, and being restored. The book is intended for people working on their restoration projects and therefore has a lot of detail shots and maintenance info.
I live in London but I didn't know they did route runs where a lot of restored busses travel the original Routemaster routes!