*sigh* it goes like this:
1. If you're not 19, don't worry, you don't have to pay yet.
2. If you're at uni, get a HC1 form (need to ask doctor or get online) fill in and send back with details of what you get. Don't be tempted to lie, the NHS are EVIL and will check. They check EVERYTHING to suck out your money like the IR do
3. You might be lucky and get a HC2, which gives you money off stuff from the NHS like dentists and prescriptions (but beware, I get Incapacity and I'm still expected to pay for my scripts)
4. If you're working, I'd suggest getting health insurance of some form to cover le dentist, or set up a payment plan with them, and get a pre-payment certificate if you need prescriptions on a regular basis.
100s of personal statements examples here