many years ago (in a different millenium) i was trying to decide if i should drop A-level maths. people said it was an important subject and i'd regret it later. well i dropped it and had more time to get pissed and have fun at sixth form.
i still went to uni, got a good degree, and haven't regretted it at all. hell i even dropped out of uni twice before i got my degree. i dont even have my gcse certificates anymore, or my a levels, i did well in all of them but no one has asked how i did or to see my certificates apart from applying to uni.
"new" uni's will let you in with 5 gcse's and 1 a-level these days so why worry. have fun and enjoy been young, there's plenty of time to pull your socks up in the second and third years of uni. as long as you get a 2:1 degree anything that happened before it is pretty worthless. employers wont care what you did at school or college, they wont even ask once you have a degree. if only i knew then what i know now...