lol I was only kidding, of course uni will be a completely new experience compared with school - and I know what you mean about school being insular. There's only 120 people in my year too (and next year I think we'd be down to about 90 by the looks of it). Still, I do enjoy the homely feel.
Anyway, back to the topic at hand - if I was in your position, I wouldn't change schools. My sisters changed school for Year 12 and they found it hard enough to make friends, and they took about a term to get completely used to it... and you don't want to lose precious time for friends etc, when Year 13 is such a crucial year. Plus, what will happen in regards to references? The teachers at your new school probably wouldn't know you as well. Still, if you want to go for it, I'm sure there are ways around it (as the OP mentioned in the first post). In the end it's up to you!