Air Traffic Control - Graham Duke - Google Books
I had an earlier edition of this book by Graham Duke which was excellent. I believe the author has frequented these fora in the past. The latest edition seems to be out of stock on the usual online bookseller (except for a very overpriced used copy!). Be careful with old books as this game changes quickly so a lot of them will be drastically out of date. Also be wary of books from other countries, I found lots from the US (including test-prep types) which will only confuse you. If you are going for a career in ATC, don't worry about reading the actual manuals etc. until you are at the college - you'll only misinterpret or mislearn stuff that will prove hard to undo later.