Hi ACARS
I echo what Joel has said. In my case I too used the Trevor Thom books (it doesn't matter, the others are as good), I did a module at a time, and because I was doing the NPPL(M) exams I used the test questions from Wriggley's which were superb.
What I don't mean above is that you follow the NPPL route, but that the method of using a set of questions to drive your revision & show you when you're ready can work very well. The questions really do guide your revision and make reading the books much better.
I'd also suggest that a couple of general flying books, search on these forums for recommendations, make a useful break from revising whilst keeping you in the mood. Alex Kimbell's "Think like a Bird" is really good, but addictive. Beg or borrow a copy but put it well out of reach when you're revising