Hi Butterfly1987,

I've not had a colonoscopy myself but I've had a lot of experience as an Endoscopy Nurse and now work as a Specialist Nurse in bowel cancer screening, so I'm hoping I can help put your mind at ease a little.

I can't lie to you, a colonoscopy isn't the most pleasant of experiences, but it is the best test for finding any abnormalities in your bowel. 
The test itself involves navigating the bends in your bowel which can cause some cramping - people tend to liken it to period pain. In order to get a good look at the wall of your bowel, the endoscopist with need to inflate your bowel with carbon dioxide which can make you feel bloated, or like you have trapped wind - the endoscopist and the Nurses will likely encourage you to pass wind if you feel uncomfortable. 
If the team find any polyps (growths inside your bowel) that need to be removed, and can be done so safely, they will do that there and then and if they did for example see a cancer, or any other abnormalities, they would take some biopsies. Removing samples of tissue or polyps doesn't hurt.

because of the length of the procedure (usually 20-30 minutes) and the potential for discomfort, you will be given the choice of having a sedative and painkiller - injected in to a vein to help relax you (you would still be awake for your procedure) or gas and air.

you will be told the results of your test on the day so you know exactly what has been found and the endoscopist will arrange further tests if needed. 

It's also worth mentioning that the majority of people who have this procedure done don't have cancer.

Best wishes and I hope this isn't too long a post.