I'm in the same boat as you, passed GFPT about a month ago, got 172 endorsed on Sunday and have Nav1 booked (be good to finally get out of the training area!). I got all the bits & pieces I needed like charts, nav comp, wac ruler etc and picked up the PPL VFR study guide by Bob Tait because I heard it was good.
I used the ATC Student Pilot Kit previously, but going through this PPL book is much much much easier, very clear and explains things in terms 'beginners' can understand. As all the others before me said, can't go wrong with Bob Tait.
Congrats on the GFPT pass, hopefully many more to come..
Cheers