I imagine that it's something that you'll have to discuss with your school as obviously they will want good A2 results for the school so it's a risk to them i suppose, if you can convince them how keen you are then i shouldn't see any problems with it!
I think they will let you take 1 maybe even 2 but 3 will be unlikely as along with A2 (which are of course harder) will mean too much work/risk on their part so maybe a compromise is best!
good luck!