I am guessing that this is the same thing I had last year, which was referred to as a "free soft tissue graft". It was a breeze. It took about an hour in the dentists chair. The anesthetic was just a couple of tiny little pinches and after that I felt nothing! Sat there very relaxed while he did the procedure listening to the radio which was playing in his office (I remember they were playing a lot of great music that morning). They actually took a tiny piece of tissue from the back of my mouth and attached it to the tooth where I had bad gum recession. When it was over they just stick a small bandage on the tooth which I barely felt - that stays on for a week. They also sent me home with a prescription for pain killers, which I never needed to take. There was no pain! They tell you to be careful of aciddy foods for the first few days, because they might irritate the spot where they took the tissue from, but really I had no trouble eating. I'm actually having another tooth done at the end of this month and I'm not worried at all. Relax, it will be fine. If you have any other questions, feel free to ask me.
Also, just wanted to add that I drove myself there and back, and went about the rest of my day as I normally do with no problems.