I don't know about what climate you're used to but the UK is quite wet, windy and cold, and so my main advice is to bring a waterproof coat with a hood. You will also probably want some hoodies or jumpers to keep warm even when it's not raining.
it can be pretty variable here so you'll need clothes for a few different things. 1x suit and tie for things like freshers ball and stuff 1x pair of flip flops fo the shower. 1x swimming costume (the summer can be fairly warm and we sometimes have heat waves 2x pairs of shorts again it can get hot some times
usually it's cold though so. 10x t-shirts 4x pairs of jeans 3x hoodies 3x sweat shirts as much underwear and socks as you can. 1x Good jacket ( you'll probably be here in September so buy it here I usually use a ski jacket) 1X pair of ski or snowboard gloves or mitts 1x Pair of Snow pants (it snows here sometimes) 1X pair or thermal underwear. 2x pairs of trainers 1x workout gear 1x rain coat.
Does that help. At uni make sure you get a university hoodie for your university there so warm and comfortable.