It honestly won't be as bad as you think it'll be. Of course, you will be nervous - I think anyone would be, no matter how many procedures they've had - it's natural. You will be well looked after and once you're out, the hard work is done by those caring for you. And yeah, you might be in some pain when you wake up, but that will be a controlled by a team who are trained to do so and you will have a lot of aftercare. Ultimately, if you've been told you need surgery, then you must; I would imagine that the nerves and anxiousness about it are a small price to pay considering what may happen if you don't go through with it.
I've had quite a few surgeries, my most recent being knee replacements (I'm thirty - an old, old lady). Obviously I had no idea what it was all going to be like, but it was alright y'know. I think the best piece of advice that I can give you though is to not Google anythinggggg!