DD1 is in Y9, so perhaps I have all this to come next year, and it will be all different, but this is what we do at the moment.
She doesn't go out randomly with people I don't know at all, well, perhaps the exception would be say for the Christmas lights switch on in the local town, she went with a few friends and there were some other kids there they met up with who I don't know, or very well. They came back on the train (two stops) at about 8.30pm and we picked her up from the station.
Other than that she and her friends have parent-supervised parties and sleepovers. Usually all girls, they go to a girls school. Parties usually finish at 10pm and are held on a non-school night, I don't really have a curfew for when they have to be asleep at sleepovers, though I make sure there is nothing important on the next day. Sometimes they've been in bed by 10.30, sometimes DD has been up until all hours at friends houses.
If she was going out somewhere with friends later in the evening, say to the cinema or cafe I'd want to know exactly who with, who else was likely to be there, and would want her to be picked up either by me or another parent, not too worried about the time depending on what was happening the next day, but probably 10.30/11pm would be late enough.