1) even though you will be told many times first year doesn't count, try to get to as many lectures and seminars as you can (even if you are in a delicate state!) Try hard in the assignments as this really prepares you for the next 2 years, and looks good on your transcript. You might even enjoy learning...
2) That said, make sure that you go out often, join a new society or sports team and make the most of being a fresher! Joining a sports club was the best thing i ever did (even though i hadn't played for years), you meet so many new people and get to do some great things. I would recommend it to anyone.
3) if you feel homesick or that your course isn't right for you, talk to someone. Too many people quit without making the most of the extensive pastoral care networks universities have. Homesick usually passes and they can advise about the course, talk to your tutors as well- they want you to succeed but can't help if they don't know you are struggling.
I am really jealous of everyone starting this September, I had the best 3 years ever!