I know where you are coming from I went back to college a number of years back as a mature(ish) student and for weeks beforehand I was a nervous wreck even although I am usually quite confident in the company of most groups of people.
When I got there I found most of my fears were unfounded (apart from the fear of teachers who wear black high heeled boots) of whom fortunately there were only a few LOL.
Once you get there you will be fine the first day nerves will pass you'll meet loads of people who were probably as apprehensive as you were.
It will be loads of fun and laughs with a sprinkling of learning thrown in .
If things get a little tough then you always have us lot on here to turn to for support, although I am not too sure if that will be a comforting thought to you LOL.
As for mixing with your peers we have an old Scottish saying "We are a' Jock Tamsons bairns" meaning nobody is better than anyone else we are all equal (apart from Mrs NCM who is a wee bit more equal than me) so get stuck in there and remember you don't have to prove anything to them, just to youself.
I for one am absolutely certain you will do really well.

All the best to you.

NCM