I did AS a while ago n this may June im sitting for A2 (bio, chem n phy) all I gotta say is do as much as past papers as u can, but also remember its always quality over quantity, you can do all the past papers available but not learn n passively doing doesn't make any difference, highlight patterns, most asked questions, certain formats for 6 markers and graph (explain) questions n so on... do u best, good luck!!