You can have surgery and whatnot without notifying your parents at 17. I had an operation in the same area when I was 17 (not circumcision) which I did not tell my parents about until I was already on the waiting list. NHS letters will come through the post though - keep that in mind. I told my parents in the end out of choice, shortly after organising the surgery (on the NHS), since I figured it was only fair despite the somewhat embarrassing subject. They were totally understanding and made nothing embarrassing for me.
If you are having a general anaesthetic, then it will be hard not to let your parents know given the time you will spend in a hospital bed, and remember that someone has to pick you up afterwards. For foreskin-related surgeries, remember that some hospitals do indeed give general anaesthesia by policy - I got that for mine. Usually you can't choose between local or general - it depends on the hospital policy.
And as has already been said, though I've not experienced a circumcision myself, you'll be in a damned amount of pain. There's little chance they won't notice your efforts to conceal it. Just do what I did and let them know - you might be surprised; they might be very supportive just like my parents were. It's not exactly an easy thing to raise to them after all, surely they'll understand.