What actually happens by the way is:
You are given bowel prep medications to take a day or two before, with strict timing instructions. Follow these to the letter.
On arrival at hospital you'll be asked to change into a gown and (if like me) given a pair of blue paper knickers with a hole strategically placed where your bumhole is lol.
A nurse will check your details, take a brief history including allergies, put a name tag on your arm and you may have a chat with whoever is going to give you the sedation. (I was given midazolam and fentanyl, some people are also given buscopan to relax the bowel).
When it's your turn you'll go to the procedure room where there will probably be a few staff (three in my case, mix of male and female) where you'll be settled, a cannula will be put in your arm, you'll be asked to lie on your left side, the sedation will be administered and the doctor may just have a feel around the inside of your anus.
The scope will then be introduced (feels like having a small poo in reverse) and you will be aware of it being there but it shouldn't hurt. By now, the sedation will have kicked in and you'll remember very little of this a day or so afterwards.
They scoot the scope around your bends, take pics, chat about your hobbies or weekend, maybe take biopsies (should be painless) and pull it all out taking pics on the way.
Back to your hosp bed for a snooze if needed (I didn't) and you will need to be driven home. All done!