I didn't want to go to my insurance either, and I thought I was gonna fail my maths. Here's what I did, on the recommendation of a family friend who did fail to get in to his first choice the year before.
1) Get your grades as early as possible.
2)If you've got in, don't worry.
3)If not, you need to have done a bit of prior preparation, a la Blue Peter; namely;
-1)Find out some unis that you would be OK going to, that have grades (or a range of grades) you think you might have got - for the course you want.
-2)Find out contact numbers for the departments, make sure that they'll be answered on the day. They will be busy.
-3)Put the places in an order of preference for each situation (e.g. "if I get ABC, I'll go for unis 1 2 and 3; if I only get BBC then I'll not have a chance with 1, so I'll go 2,3,4, if I get BCB, then 3 won't accept, so 2,4,3 etc etc.)
4) On the day, when you get the results, be ready to get on the phone to your top choice uni ASAP. You're supposed to phone up your insurance first, but don't bother with this. Technically you have a binding contract to go to that uni, but if you don't want to go, they're not going to make you. No uni wants a student that doesn't want to be there.
5) Once you've found somewhere that'll give you a place, phone up your insurance and tell them you don't want their place, but don't do this until you're 100% sure that you've got a place at the other uni.
You're not supposed to do it this way, but just claim you didn't know that, and do it this way. The lines will get very busy, very early, so get in quick!
Hopefully your results day will be like mine, you'll be all ready to spend the day phoning up unis, and then be somewhat surprised to have got in to your first choice, but doing the preparation and looking at other choices that you have will settle your mind and give you something to think about other than "OMGOMGOMGOMG" *breath into paper bag*.
Best of luck, whoever you are, and hopefully my advice will be totally needless.
EDIT: Go out with your friends a lot, Watch films, listen to music, do anything to take your mind off it when you don't need to think about it.