You need to think very carefully before getting circumcised. There are different techniques for the actual circumcision procedure and you need to investigate all the pros and cons, like loss of sensitivity for instance.
You will first need to see your GP unless you approach a specialist clinic directly, even then your GP will be involved. That would probably be your main source of information anyway.
Your parents WILL need to be involved.
As you live in the UK you may get the procedure done free on the NHS.
Try looking up some of the clinics on the internet at least they will inform you about the procedure.
Index of Some Clinics
One Example
Personally I’m uncut and I want to stay that way.