Trust me, it will be *awesome*.
I moved away from my parents to go to university when I was 18, and it was the best thing I ever did. You'l feel a bit homesick for ther first few days, but as you say, you'll be in a dorm with lots of other people in exactly the same situation, so it won't be long before you're all friends.
I find it funny looking up people I used to know on Facebook to find they're still living with their parents in the same village despite the fact that they're now in their 30s.