Hi I had one of these in April. There's absolutely nothing to worry about with regard to the actual procedure, mine was painless, the staff were kind and it's all very quick. It does feel a little odd for literally a minute or two when the x ray dye is injected and some people experience discomfort with the carbon dioxide used to inflate you but I didn't. Best advice is stick to the diet absolutely or it may not be possible to get good images. Drink some lucozade sport as it contains electrolytes , take some with you. I felt tired and light headed because I'd kept hydrated but needed electrolytes! This was recommended by the radiologist but not on the instruction sheet.
Tbh I think you get results quickly if there's a problem. I got a letter Two weeks later telling me all was ok so don't worry if you're waiting, no news is often good news. The really good news is the scan looks at the whole abdomen so a clear scan is extra good! Best wishes for a positive outcome.