Have a look at
JAA - Licensing: Learning Objectives IR (A) to check out the topics you have to know.
I used the distance learning course from Nordian. The books read like novels. They are less detailed then the Oxford manuals, but for the PPL/IR it is sufficiënt. A lot of the Law-course contains stuff you don't need to know (PICAO, ICAO, blah blah,...).
The most intense exam was Flight Ops/ Planning but you can't really study for that one. Meteo is of considerable size but I found it rather interesting.
You can find the Q&A databases for free on the net. But these are based on the ATPL exams. If you can manage these the actual exam will be a piece of cake.
Go for it and good luck !
