My experience at a sheffield offer holder day was extremely good, even though I was very unsure if I wanted to go sheffield university, like the people at it made it seem like a very nice place, I met some second year dude and we like instantly clicked, he even told me I should let him know if I'm coming to Sheffield he will introduce me to everyone ahah. All I can say is you don't have to worry at all, everyone is very welcoming and I think you'll be fine in finding lots of friends just even walking around in the departments, or maybe I just got lucky lmfao