The national recommendation is that you take FOUR subjects at AS level (ie, the first year of sixth form/a levels) and dropping down to THREE for A2 (ie, the second year) this is the NEW system called "cirriculum 2000" or something......it used to be you just took 3 subjects over 2 years, but the new system is to 'broaden' your knowledge...or some garbage, it just means you take exams (if you go to uni, and dont take a gap year) for 7 years straight. urgh.
anyways, so if you were to take all those subjects to AS...you would be taking the equivilent of 5 AS levels...which although far from impossible (someone at my school took 10 at AS and 9 at A2....gaining 6 As and 3 Bs...WOW) is going to leave you with ALOT more work than your friends.
Talk to your freinds, parents, and college about it!
Hope this helps. xxx