It may be more than six months before UCAS forms start being submitted for the September 2012 University intake, but it is never too soon to start thinking about how the application works.
The first three steps which you can start on now are:
1 - decide which course you would like to study
You will be studying your chosen course for between 3 and 5 years, make sure it's something you are interested in and have a natural affiliation with.
2 - short list which universities you would like to attend
campus or city?
relaxed or formal?
near to home or further away?
Start to think about how you feel about those options and perhaps visit a few universities to get a feel for what they are like.
3 - register with UCAS
You need to register with UCAS if you want to apply to university, they handle all the applications.