Try not to worry, I have had this procedure regularly, and it is really fine. I would go for the sedation, you are not really aware of anything, you are given a gown and underwear for modesty and it is really quick. It is not painful at all.
A couple of days before you have to stick to a very simple diet ( they will tell you what to eat) and then you take a laxative mixture to clear everything out, so to speak, so on this day you may want to stay at home near the loo!
If ever I am not looking forward to something I always plan a treat for afterwards, so there is a plan to look forward o, but you will be the other side of this in no time, and it is really fine??