There has been a lot of stuff posted over the years on pre course study so do a search. I think you will probably find some info on the various websites from the schools that offer ground school as well that should point you in the right direction. Manipulation of algebraic formulae to a reasonable standard (nothing to hard), having a fair idea of how the CRP5 works and a bit of basic physics should put you in good stead. Failing that read over your Trevor Thoms. There is a surprising amount of PPL level stuff that crops up in the ATPL's that you generally skipped over without completely understanding.