I went to a mixed school but PE (that's usually what sports class is called in the UK) was always separated into girls and boys, we also often werent allowed to play the same sports, boys usually played football and rugby, girls usually played netball and rounders. One time we played dodgeball with the boys and I hated it because of how much harder they could throw
It's funny but I think you can definitely tell when someone went to an all girl's school. I knew a girl once who was really nice but I wasn't surprised when she said she went to one, she just gave off that vibe