I've been there op - had the whole lot out due to IBD and various surgeries since. Remember being terrified before one in particular, the theatre team were so kind and good at helping to put me at my ease.
I'm not sure I really coped! I had a meltdown on the ward the night before and was physically shaking when I arrived in theatre. If you're that bad you can ask for a valium or similar to help beforehand.
You just have to trust that it will all be OK and they know what they're doing. Drifting off under GA is weird but quick and actually pretty nice. You don't know anything after that.
You'll likely feel some pain when you wake up, that's OK, they can adjust your painkillers via IV very quickly. My more recent experiences coming round in recovery have been much more pleasant, it used to be quite an abrupt awakening but they seem to treat you more gently now.
When you get to theatre, you'll be in a room where they give you the GA. You'll be in a bed and they'll insert a canula and attach an ECG (sticky pads to your chest) so they can monitor your heart rate.
Good idea to tie your hair back- no metals, just a tie - and not too tightly. You want it out the way but comfortable.
It can be nice to apply a nice moisturiser to your face that morning so you feel you're taking care of yourself. Keep your nails free of polish.
They'll ask you your details - name, dob, allergies etc and check against your wrist band. The GA will probably be iv and they'll probably hook you up to oxygen and tell you to breathe evenly. They might ask you to count backwards and you won't get far before you drift off. When the GA goes in you might feel a bit weird in your arm or a bit tingly and that's probably the last thing you'll register before you wake up later.
I don't regret any of my surgeries, they were all worth it. You'll be OK, just tell them you're scared.