OK I'm going to rub some people up the wrong way here, but if you're going to go and do ATPLs pretty soon after your PPL, then you MIGHT want to consider just getting the bare minimum in terms of Trevor Thom books and the PPL confuser. Most flying schools have got a load of TT books kicking around that you can borrow.
Yep, get a CRP-5 straight away: check eBay for these useless pieces of plastic. Don't bother with the CRP-1, it's even more useless than the useless and horrible CRP-5, which is useless (or did I mention that before?)
I'm a firm believer for doing everything on a shoestring (Michael O'Leary eat your heart out), so again look at eBay for things like your square protractor and knee board. You're right about the leather flight case: leave it until you've got serious amounts of kit to transport.
I use, and swear by, a Pilot PA11-20 headset with Oregon Aero ear seals. Headset is worth buying new... or s/h unused if you can find one. I also use some sunnies I found in Blacks (Outdoor shop): Stone R-67, which fit perfectly my head with my headset. It's a very personal thing, so find a headset you're comfortable with, and then find some sunnies that fit nicely with that headset. Remember: headset first, then sunglasses.
If ever I need to buy stuff new, I use
www.pilotwarehouse.co.uk because they always tend to be cheaper. AND they give a 10% discount to BALPA members (I think).
Which reminds me. Contact BALPA for student membership- there are LOADS of benefits to joining. And ask them for details about your loss of Flight Instruction Fees insurance: it's cheap (about £10/month for someone under 30), and if your medical goes the way of the dodo the day before your IR test, you can claim some or all of your flight instruction fees back. BUT you need to take this insurance out BEFORE you start training, otherwise you can only claim 75% of your training costs if you lose your medical.
Can't comment on the Oxford PPL CDs, never used them. However if the Oxford Met CD is anything to go by, they should be pretty good.