I had one a couple of months back and, like Canada girl, had a relatively easy experience. Process wise, it's very similar to having a smear whereby you strip off bottom half and lie on a bed with knees up. Sonographer (? I might very well have the wrong professional there but the very nice lady who carried out the process!!) gently inserts what feels like a soft slim conical object into your vagina, wiggles it around a bit and takes screen grabs of what she is seeing. The lady who carried mine out was wonderfully gentle and explained what she was doing.
I had been very nervous as I have vaginal atrophy and lichen sclerosis so am pretty tender all around my vulval/vaginal area but she clearly knew what she was doing (of course!!) It was a little bit uncomfortable but not as unpleasant as a smear is these days!
Please try not to worry, I know we all do! I hope you have as good an experience as me x