i'm from a very small town as well (i think the populations around 7,000) and i know exactly how you feel. When I got in to highschool, i thought the same thing, and was worried about every little thing I did. But the truth is, no one really cared anymore. We were all worried about our grades and our own lives that no one paid attention to those little petty differences like whose more popular than who, and who has better clothes.
I guess what i'm trying to say is that you'll be fine. Just be yourself, and from what i've seen on this board, that would be a really cool person. As long as you have confidence in you, and forget what other people think, you'll be fine.
I hope you have an awesome year! that's cool that you get to leave whenever you want to....our highschool is like a freakin prison...i won't go in to the detail, but it's not fun. thankfully i only have one year left..... 177 days and counting.....