I just finished my art gcse this year. It was very enjoyable, after the first project we were virtually allowed to do what we wanted as long as it relates to the set topic. You get to experiment lots and find which media is best for you.
I never found art stressful or got behind on work. I also compete at national/international level for sport and had to balance training as well as 12 other subjects. If your organised it shouldn't be a problem. Use your lessons and don't just sit around and chat (some people I know did this and got quite behind!).
Best of luck!
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Or does it play no part?