Hello
i had this operation last october, a few months before I was 18, free on the nhs.
Considering your age, you'll only have to tell your doctor it bothers you, then you'll be referred to a consultant, whom will then finally decide if you are worthy of the operation. Then you are placed on the waiting list, but many trusts give a specific date when the operation will be carried out, just like mine did. However, it was cancelled on two occations, but that's the nhs for you.
I finally had it done and was impressed with the results, however, after a few weeks went past, the operation wasn't as successful as I thought. Despite this, most operations are successful.
So go to your doctor immediately, he will refer you, then all you have to do is wait and prepare your self.
Good luck.