Having just sat and passed Air Law and OP rubbish with the CAA I have to say that the question bank from Bristol was extremely useful.
Learn you stuff well and then with a month to run get yourself into 'exam' mode by sitting mock after mock with the question bank.
(Hint, 9 out of every 10 questions in the two exams I took I had seen before!!!!! But be wary the CAA changes a couple of things every mow and again so this method is not recommended. Good overall knowledge wins out every time
)