The best

My exchange started in September 2016 and since than Brigton has a piece of my heart. The first week was stressful for me and I believe it is stressful to everyone, but the Uni has a lot of lectures that will give you all the anawers you need - about the UK, grading system, what to expect and what is expected from you. Everything is clear and if you need more help, you can always go to the International office or ask a professor. It is easier when you are there than thinking about the exchange at home. Also, there is a lot of activities for students such as gym or one day trips. The city itself is unique and you are never going to be bored. People are friendly and helpful.
If you are thinking of doing an exchange in University of Sussex, don't overthink it, just go. It will be worth it.
The Uni is amaizing, big campus with beautiful library, study places all over the campus and great student who will be your colleagues.