Need more things for my CV?

Hey, I'm approaching year 11 in school now and have to start thinking about Sixth forms, universities, jobs etc, so i will need to write a CV. I get pretty good grades at school, but my CV would look much better with some extra-curricular activities on it. I was wondering what kinds of things i could do? I live in Birmingham, and was wondering if there was any volunteer type work i could be doing. What other things could i do that would look good on my CV? Thanks.