I found that the FP&P exam was a "mop-up" subject; all the areas not covered by the other subjects. I did not find that there was any one particular book that helped.
However, it will also help to get quite a few hours of flying under your belt as well and much of the subject you will learn form your instructor. Get your instructor to explain procedures as well such as completion of the Tech Log etc.
As Pofman says, pass some of the other subjects first and it should all come together.
Cheers
Whirls