Books: EBAY has most of them but see which ones your school uses both are as good as each other.
eBay is fine, just make sure the Air Law book is as up to date as possible. With EASA taking over from the CAA, there are loads of changes at the moment. Also, I don't know how up to date the CAA exams are in this respect. But a three-year old Air Law book is worth less than the paper it's printed on.
As far as the rest of the books series is concerned: No problem to use books that are slightly out of date.
Don't go near Jeps charts until after you have got your PPL.
Despite being a big fan of the Jeppesen charts, I agree with this. The advantage of the Jeps charts is that they have a uniform presentation across the whole of Europe, and quite a few places beyond. But the nav books, nav exam and other materials are all based on the CAAs interpretation of the ICAO way of presenting things, so it's best to use those charts initially. You can always switch to Jeppesen once you got your PPL and are going abroad.