As far as books go ask your school. Different schools have different preferences. The Air Pilot's Manual series are very common, and reasonably priced. You can pick most of them up on eBay for peanuts, but buy a new copy of Air Law as that changes over the years. Apart from that you'll need:
CRP-5 (don't bother with a CRP-1 if you intend to go commercial)
Ruler (calibrated in nautical miles)
Protractor (preferably a square one)
Some permanent pens (and some nail varnish remover)
A 1:500,000 chart covering your area (although wait until you need it before you buy it, or you may never use it before it goes out of date)
A kneeboard. Get one with a hole punched in the corner for stopwatch mounting, you'll need that for instrument flying. A4 is a better option for when you need to start calculating diversions in-flight. A3 need strapping round your leg and if you've got rugby thighs you'll soon find it cutting off your circulation as the elastic is never long enough!
PPL confuser. Useful for getting into the mindset of the exams.
Get the best headset you can afford. I've used all sorts, but having got a Bose-X set I can honestly say nothing I've tried even comes close in terms of both sound quality and comfort. The sheep seem to be obsessed with David Clark, but I find them horrible things which clamp your head like a vice.
Most importantly, you'll need: Lots of money.