There's a time to play, and there's a time to study.
Of course it would be too much for anyone to study 24/7.... but at
the same time, know your limits when it comes to playing. As a
general rule, if you feel that your playing is getting in the way
of your studying, then you should reduce your playtime.
After all, you only have one shot at the A Levels.... don't end up
regretting and whining that 'I should have studied more' in March
next year.