Most people in the UK dive in a drysuit. I did my AOW in an ill fitting wetsuit in Cornwall in May many years ago and can still remember the water pouring down the neck where it didn't fit very well. Since then my dives have all been mostly dry apart from when my zip started leaking badly.
You do see some people on boats doing shallower sites but I've always been of the opinion that they're mad. However, I recently drove down to Cornwall for a weekend's diving. Two hours down the road, I realised that I had somehow managed to forget to pack my drysuit and the only option was going to be to rent a wetsuit. It did at least fit and it was August, when the water is at its warmest. My dive computer registered 15.8C, which was less than the 18C I'd experienced further east the previous weekend, but about as warm as the water in Cornwall ever gets. The dives were the Mohegan and Volnay, so not deeper than 25m, so compression of the wetsuit wouldn't be a huge factor.
Rolling in, and the cold rush wasn't that bad. In fact, for the first 20 minutes, it was alright. Then I started to get cold. By 40 minutes, it was starting to get to my limit and by 50, I'd had enough and we came up. The RIB ride back wasn't too bad and back at Mylor, I dried myself, put dry clothes on and had an hour and a half for lunch.
Putting the cold wetsuit on for the second dive was as delightful as ever, but it wasn't that cold. The second dive was much the same as the first though my limit was reached in about 40 minutes rather than the previous 50.
So would I do it from choice in the future? Of course not. In my drysuit, I wouldn't have been cold at all. I think my limit for wetsuit diving is about 20C. I did a couple of days in Lanzarote in December in those temperatures and that was OK. 4 degrees less is quite a significant difference. 10C in winter would be horrible.
Drysuits do require a bit more training but once you've got the hang of them, which might take 20 or so dives, they're really just as comfortable as a wetsuit. They are expensive, though it's worth checking out the second hand market. The only other downside is that they can get very hot in the summer on the surface, but sadly this is rarely a problem in the UK. On the odd day it is, get the skipper to chuck a bucket of water over you.