My piece of advice would be that you really should not sleep with anyone who shares your accommodation or friendship group, things can get really awkward and it can create tension in your flat! There is plenty more men out there!

York has a half-decent nightlife depending on where you go and on what night. Not as exciting as say Newcastle or Manchester but still alright. And you will know where is good etc after a week or so. It can be rough depending where you go and what is on e.g. York races etc.