CONNLABOI..... Like yourself I was apprehensive of this procedure for very same reasons, I too explained my apprehension to the Radiologist who was very understanding and helpful but after the 10 to 15 minute procedure, which consisted mainly of laying on a X Ray table and waiting for results, I realised my apprehension was unfounded.
The tube used to insert the dye is so thin, it wasn't even noticeable during its insertion or through out the procedure.
My J Pouch surgery and this procedure was performed on the NHS, so I woukd assume the entite procedure will be identical to what's performed in Northern Ireland.
I'd suggest you still inform the Radiologist and Nurses of your apprehension; in my case, doing so made all the difference, I was reassured throughoutand each step was explained; I was even shown and able to feel the tube used beforehand.