My advice: don't bum off maths and physics (or chem/bio, if that's where you want to go). I'm in my first year at university, and bummed around a bit in school. 'As long as I can get good enough grades to get into uni, that will be fine, then I'll nail the As at university'. It didn't work for me, nor for anyone else who has tried.
Baaad move. I started behind other people, and I'm struggling to keep up. Now I feel like a completely wally for not learning properly in school. Honestly, what you do in school directly affects how well you do at university. Just try as hard as you can now, so you don't have to struggle later.