Hi Silversky. I know exactly how you are feeling, and as everyone else has said, you certainly won't be the only one!
I know it's a bit patronising and trite, but your GCSE results AREN'T the be all and end all. You have been accepted into college, from what you are saying, so you have been really proactive in considering your dreams and your future. Take comfort in knowing that you are all organised and ready to take on the world :)
ALL of you should be excited, not just half! You are embarking on a whole new part of your life, and you have so many opportunities ahead! I chose to go to art college to do my a levels, rather than 6th form like everyone else, and I knew nobody. But I met some really amazing people, and had a very special time. When I started Uni, I had just moved house, so I had no friends! I also commute to Uni, so wasn't familiar with my surroundings at all. If you treat it like an adventure though, rather than a chore or something risky, you'll see everything positively.
In terms of sleep, Pollianna's idea is great-I am forever writing things down! It sounds like you have a lot on your plate, you must be v. popular :) Try and prioritise, and put things into boxes (metaphoricallym or even physically if it helps!) in order to help you deal with one thing at a time. If you approach it this way, then you'll feel less overwhelmed by everything.
I think you are a lovely person, and you have a LOT going for you, so lots of luck and warm wishes for the coming year :) x