Class that meet 3x per week - 50 min each, 2x per week, 1 hr 20 min. So at least it's not any different than if you were in school here
That's nearly the same except that for an 11-week semester (as was my undergrad), you only have 2x 50 minute classes per week per 10-credit course/class. For a 20-credit class you might either have 4x50 minutes per week for 1 semester or 2x50 minutes per week over 2 semesters. However, at Bristol, they run on 6-week teaching blocks, so you might have 3x 50-minute classes per week for 6 weeks instead of 2x 50-minute classes for 11 weeks.
The main difference with class schedules is that in the US you get MWF classes (50-minutes) and Tu/Th (1hr 20min), which are scheduled at the same time on each day. This is not the case in the UK - classes are generally all the same length independent of the day and they are not structured as MWF or Tu/Th -for one lecture course you might have your classes on Monday morning and Thursday afternoon, but for another lecture course you might have them on Tuesday afternoon and Friday morning.
Because you don't have to worry about possible scheduling conflicting in different subjects (you usually only take classes in your major), each department usually works to it's own independent schedule and class structure.