1. The first thing you need to make sure of before leaving is that your passport is still valid and that you have all your visa papers ready. Remember to keep them in a safe place along with your air ticket. Also, make sure you have enough money or a credit card on you. That way, if you forget anything, then you can buy it over in the UK when you get there.
2. There are a lot of things you'll probably want to take with you, and there's only one thing to keep in mind when packing--don't try to take strange, locally-produced wet goods that won't get through customs. Beyond that, you can try and stuff everything you want inside the largest suitcase you can find provided it doesn't exceed the weight limit--remember to weigh your suitcase before you get to the airport or you might end up paying a hefty fine! Also, pack a change of clothes and your essentials inside your overnight hand-carry to take onto the plane, just in case there is an accident with your check-in luggage.
3. When in the UK, don't get carried away with partying and neglect your studies! Since English is not your first language, you will probably have to work doubly hard to keep yourself up to speed with all the classes. If you have trouble with anything, don't hesitate to ask your teachers for help. You might want to consider bringing a Chinese-English dictionary with you to help you in your studies.
4. Always remember to be polite when you're there! After all, you want to make a good impression for both yourself and China. Have a ready smile for everyone, and don't forget to thank shopkeepers and waiters when they serve you. When you first get there, drop by and say hello to your neighbours, and familiarize yourself with the area. Asking around is a great way to find out where the best shops and restaurants are.
Good luck, and enjoy yourself in the UK!