I just had an upper endoscopy last week. It was my second one. It's nothing like the colonoscopty. It wasn't bad at all. There isn't much of a prep for it. You have to stop some medications before hand, but your doctor will tell you which ones. The day of the procedure, you can't eat until afterwards. Nothing after midnight the night before. They start an IV in the prep room. They spray the back of your throat and give you something in your IV and you just go to sleep. It doesn't take long. When you wake up they give you something to drink. Once they're sure you're swallowing ok you're ready to go.
You can't drive at all that day. I slept off and on on the way home and napped for a while at home. You may feel like there's something in your throat for a couple of days, if they took a biopsy, but that's about it.
So don't worry too much about the test.