Ah! I thought I replied to this! I guess Pokecommunity killed my post!
Well GCSE's are qualifications you get at UK colleges. (I don't know much about that because I was born and went to school in Canada, actually..) but to be an animator you just need to have very solid animation skills- shown with a demo reel.
I learned 2D animation throughout uni.. and we did do like 3 months of 3D animation as an introduction, but I basically taught myself. If you have strong 2D skills, it is more likely you will be able to bring them over to 3D. But don't worry if you're not the best at 2D.. I know some great 3D animators who can't draw. Drawing helps but it's not everything.
Solidify your animation skills.. so.. balance, weight, timing, spacing, etc.
I recommend doing stuff on your own, too! Do you have any work that you'd want to get critique on?
I think joining the 11 second club will also be great practice too- you can get feedback from fellow animators there, too. (Check it out.. just type 11 second club into google.. it's a cool site.)
I worked my butt off because I wanted to get better myself. Not all the teachers or resources were good at my school, like yours, but if you're willing to work hard you can achieve it!