Nothing is 100% guaranteed to be on a paper but Air law is just a fairly dry learning exercise there are no tricky concepts to worry about. I learnt mine out of the Pratt Books which are excellent but I'm sure what you have is just fine.
3 months is absolutely huge amounts of time, if you really concentrated on it you should be able to learn it in a couple of days. Make sure you don't gloss over the hard facts, learn what VFR minima is in all the airspaces, the wake turbulence spacing requirements, hand signals, quadrantal rule and so on. Believe me I have met some absolute idiots who passed, its a hell of a lot easier than the GCSEs that I assume you're revising for.