I have not been active in the UK yet, but other countries I have hit I will most often go for multiple hours depending on the situation.
Really what it comes down to is I don't like to be rushed. If I am having a good time and not ready for it be be over, I don't want to worry about the clock. Most often the meeting starts, sex happens right away and I will spurt once in about 30-40 mins, afterward we will chat for a bit, I will enjoy her body, and so on. After about 20-30 mins or so I can be ready to go again, and this time it will take longer. This really is where I enjoy myself as I am not having to fight the urge to cum. The 2nd pop is always the best.
I have gotten lucky a few times and found girls I really hit it off with and the conversation has been wonderful. Other time I have found myself in a spot where I just ask her to leave because its over, and I am ok with it as I planned on spending that much in the first place.
Most of the time when I partake its on the road where it will be the first and last time I will be able to see the girl. If it was local I could see myself doing a 1st time for an hour and then picking the better ones for the longer sessions. But I don't get a ton of chances, so I need to take advantage of the ones I get and not rush.