I did mine years ago while working full time as an IT contractor.
I did mine with OAT.
I would agree 110% with paco about the class room based learning it doesn't so much teach you the thoery it focuses on the way these buggers think who set the questions and also the gotcha subjects within each topic.
I can't really comment on subjects because the hard ones seem to change on a cycle depending what they have put new in the question banks.
You just have to form a study plan and realise the fact that 6-9 months of your life is going to be lost to study. Yes have some time off and set yourself cool down periods eg bit of hour building here and there to remind yourself why you are doing it.
The content really isn't that hard its about the same level as age 16 exams in school. Its just the volume of the stuff which causes the issues