You mentioned your dissertation and I know you’re only in first year but honestly start thinking about it now because they will just randomly ask you what you wanna do and I was so stuck😂😂
In university in the UK, 70-100% is the top grade you can get (1st class), and 40% is basic passing grade. Below 40% is a fail. Between 40-69% is middle of the road marks. It’s very confusing but I hope that helps !!