You will need to do around 300-350 hrs private study for both modules at BGS. (before the brush ups)
I do 1-2 hrs in the morning and 2-3 in evening. I work about 10-12 hrs each weekend.
I know of someone who completed Mod 2 in about 8 weeks, including brush-up and exams, but did it full-time.
The PPL books do help. I have found myself going back to basics and having a different angle. On the whole though, i have used more complex books to aid the learning process. e.g. Kermode's book for PoF, and Swatton for Performance.