Hello Alex.
When I was studying for my for my PPL written exams I got a few 'Air Pilot's Manuals' (some second hand ... but current) off ebay. I would also recommend that you buy a 'confuser' which was great help (but double check the answers as some of the 'correct answers' were incorrect
).
I would also recommend a fuel tester as you should really have one for when you fly regularly, as flying schools can get a bit cheesed off if you ask to borrow theirs. I use an A5 kneeboard for flying (which you can strap to your thigh) which I found more useful than an A4 one.