Help with resits.

I got BCC Chemistry,Physics and Maths,In that order,In AS(IAL) this year,Now I'm not aiming for 3 A*s in A-levels,At the very least BBB,I need help with deciding which exams to resit.I'm resitting Maths C12 because I got 123/200 UMS and Physics P1(78/120) and P2 (80/120).So my first question is that should I resit S1(We do S1 in our school the first year) as well?(67/100 UMS)
For chemistry I got 84/120(B grade at boundary) in both P1 and P2.Now I'm planning on resiting P1 to get a high B/A since it is easier,But should I resit P2 as well?
In total I'm currently planning on resitting 4 papers (C12 counts as one).