I had my surgery in March, and also stayed overnight. Not sure whether it was because of COVID, however, I was up around 6/7am, had breakfast, and left before 9am. They are pretty keen to get you out, of course providing that you are feeling alright, have had your medication etc. Everyone is so lovely and you don’t feel rushed, but I’m pretty sure they would sort of ask you to leave if you were still around by 10am, hope that helps x