I don't know where to start really!
University life in the UK is very different from what I have seen in the US. I will try to explain it as best I can.
Personal experience: I am a final-year student at the University of Lincoln. Lincoln is a small city with air and rail links close by. It is very easy to get to London (direct train), and if you like travelling, it is fairly easy to get to the local airports where you can get to Europe for as cheap as £10. I know quite a few people in Lincoln who go away on the weekends.
Typical Day: Most university courses run Monday through Friday and have lectures broken throughout the day. Typically, the day runs from 9 a.m. to 5 p.m., with a mixture of lectures, seminars, workshops, and tutorials. Most universities also allow Wednesday as a 'sports and society' day. It is fairly common for no sessions on Wednesdays.
Accommodation: Accommodation really depends on where you are. They are typically split into either Halls of Residence or Private Accommodation. Halls are owned by the university and will either be catered or uncatered. It is fairly rare to find catered halls these days. Private accommodations are owned by businesses. One example is iQ.
With halls or private accommodation, you will either be in a flat or a studio. Flats are shared, with anywhere from 4 to 12 bedrooms, a shared kitchen, and a living space. Flats can also have an en-suite or shared bathroom. Studios are typically one room with a bed, desk, kitchen, and en-suite bathroom.
You can also privately rent your own flat or house. Many companies offer student houses with up to 6 bedrooms. Like many other people, spend the first year in halls and the last two years in a house.
Sports and Societies: In the UK we have lots of sports and societies at every university. Just google the university, and you will see the full list. I personally did Kayaking in my first year, which was great.
If you do a competitive sports team (Football, Rugby, Basketball, American Football to name a few...) you can go to Varsity/BUCS where you compete against other universities.
Most societies and sports will do socials throughout the week. A lot of socials are typically drinking socials in the city, but not all. Socials are a brilliant way to get to know other people at university and create a good network of friends.
Nightlife: Naturally moving on from the last point about socials, the nightlife in the UK is very different to the US. If you wasn't already aware, the drinking age here is 18. This means a lot of people at university will drink (not all though, there are plenty of things to do if not). The norm in the UK is to go and 'pre-drink', which is normally round at someone's flat, then go into town to the clubs. Cost of nights out in the UK will vary based on what you do. If you pre-drink before, it will be cheaper. Entry to clubs are around £5. Drinks are typically £5/6 depending on what you have.
A lot of big cities in the UK will do student nights throughout the week, where you get big deals on your drinks.
LGBTQ scene: Very accepted in the UK. Lots of LGBTQ societies at every uni. Most cities also have clubs which are particularly aimed at the LGBTQ community.
If you want to reply to this with any more questions about UK universities, more than happy to answer.