Hi!
Firstly, don't worry about it all too much - there will be plenty of other students in similar situations to you, and even those bringing their friend groups along with them will be willing to get to know new people
I would suggest you try chatting to people in lessons, and making an effort to try to get to know people even though you're shy
Are you doing any particularly 'sociable' subjects e.g. languages? I made some really great friends through being forced to talk to them in French
Also, join a few societies and get involved in college life
There will be loads of societies e.g. sports, music, film, debate, etc. and you can meet people with similar interests to you that way too
If your college has a facebook group you could try putting a message up like "Hey, is anyone else keen to join the Karate society - it would be great to get to know other girls who are interested
" as you can get to know people in advance and then hopefully meet them at college
First day, I would bring in:
-stationary
-pad of holepunched paper
-ringbinder folder
-calculator (if you're doing mathsy subjects - but don't but a fancy new one in advance since they may suggest particular models during class)
-some sweets/ small chocolates to share around if you meet some new people at lunch
-something interesting to do e.g. pack of cards (NOT a book/ gameboy/ anything else unsociable!)
-phone (get people's numbers
)
-money
-enthusiasm
You probably won't need to bring textbooks since they may not have told you which ones you need, or if you don't know your timetable you don't want to bring in a massive bag of textbooks to find you only have one lesson that day. Also, don't buy things like a planner/ homework diary because some schools will give you one.
Your first day will probably mostly be spent doing icebreakers in your tutor group and filling in paperwork. You may have a couple of lessons in the afternoon, but you won't really be starting any work - just having an introduction to the course and being told about things like the homework schedule or how you can find their class notes online.
Good luck, you'll be fine