I have had 7 in total. The first one was following the bowel screening test, and that lead to surgery x 2.
The colonoscopy is a little uncomfortable, but you can ask for sedation and analgesia. I was given a small dose of Midazolam, some fentanyl and entonox too - this made my mouth very dry. The sedation dose helps reduce anxiety and fear, and makes the procedure more comfortable, and you can watch the camera as it winds it's way along your bowel!
I had a very tortuous bowel, and the camera trying to get along the very windy tube was painful. A lot of air/gas is pushed into your bowel too, but you pass that normally very quickly.
The nurses and staff in the endoscopy suite are key to your comfort, mine were excellent.
I think the worse bit is drinking the prep and the very frequent trips to the loo the day before. This has to be done I'm afraid, otherwise the camera cannot see clearly, no biopsies can be taken and the whole thing has to be repeated!!
I did not mind the prep, the taste was not too bad, just a matter of getting the first litre done as quickly as possible (30 mins or so), then a rest before the second litre. I like water anyway, so no problem drinking that in between, and I like mint tea, so I could enjoy that too - because coffee and tea with milk is not allowed.
If you have sedation, you will need someone to collect you and stay with you afterwards.