If you got bad results then your doing the right thing now.
Don't completely block yourself out if you can't, just balance it out and rest your brain with hobbies in moderation.
You probably have a lot of people telling you this but believe me, GCSE's are VERY important. I'm 28 and it's still on my CV so it just goes to show how much it counts for the rest of your life.
Anyway, good luck and if you ever get stuck there are lots of online material to help you - use it because in my day we never had it.