I believe that most people find that they can prepare adequately through a combination of studying by themselves and discussing things with their flight instructor, although there are ground school courses on offer at flying clubs and through freelancers up and down the country.
In addition to the standard PPL textbooks, it's worth having a look at the PPL Confuser (as an aid to learning rather than as an exam crammer), and also reading more widely around the subject of flying. Good reads include "Stick and Rudder" by Langewische(on how to fly it and especially what makes it turn), "Flight Without Formulae" by Kermode (on what makes it stay up) and "Be a Better Pilot" by some American bloke whose name I have forgotten (on decision making).
Have fun on your PPL course.