I'm not sure of the laws and stuff over in the UK, but I did find something on the NHS site which seems to suggest that minors between the ages of 16-18 are able to give consent for healthcare treatment and do not need parental consent. You can look for yourself here: http://www.google.com/url?sa=t&rct=j...72938740,d.aWw

It's a .pdf file, scroll down to page 5 for the relevant part.

Does your school have some sort of counselor that you can speak with? If so, that might be a good resource for you to start with. Best of luck, FriedChicken.