Physics and Maths Tutor focuses more on old spec stuff but that can still be quite useful. For Year 12, look at C1, C2, M1 and S1 and that should start you off quite well with practice questions.
As for actually learning it, Dr Frost does some really good powerpoints that even my teachers in school use. You could go through those before your classes and that could put you at a slight advantage because you've already covered it so it'll only really be revision in class.
As for mechanics, don't worry too much about it. Physics mechanics is more about the explanations rather than the calculations at GCSE iirc, whereas it's more calculations based for AS. If it still makes you feel kinda queasy, just remember that mechanics only makes up 16.7% of your final grade and that the pure stuff is probably more important.
hope that helps.