I wouldn't touch alcohol when recovering from surgery - it's enough trauma getting the body to be healing. Stick to water and good nutrious food for a couple of months. Your body will be much happier not having to spend time processing alcohol when it should be spending time making you well again inside.
I don't drink any alcohol at all nowadays because it does make my endo pains worse, and quite a few ladies have found that to be the case as they trial and error different foods and drinks to find what things they can consume without making things worse.
Yes you should let the Uni know - so if you need time off you can have time off without it impacting on your studies - so it can be taken in to account. Let your tutors know and the student welfare people know too.
You can print off leaflets to give to friends to explain endo if they don't know about it.
There are some on the endometriosisuk website but also smaller flyers and cards can be found with a google image search.
Tell people you have recently had surgery and are needing time to recover, (there is no nedd to be graphic or give details if you don't want them to know that side of it)
If they are mature and caring friends they will understand and support you, if they are not then don't give them the time of day because they are childish and selfish and not deserving of your friendship.
Remember too if they have been drinking they are not behaving rationally no one who is drinking behaves rationally. They may goad you to join them to not be a party pooper or spoil sport but that is the drink talking, and they are not in the slightest bit interested in your welfare but only in their selfish quest to have fun. Ignore them and look after yourself.
They will hopefully grow up one day.
Another thing to bare in mind is that over 1 in 10 women have endo. There are bound to be lots of fellow uni students with endo - some may be suffering and not even know they have endo. Others may be experienced with meds and surgeries and very sympathetic to what you are going through, so perhaps ask at the students union or welfare office if they know of other endo ladies, there might even be members of the faculty with endo. But ask around or put up a flyer asking anyone interested in joining you in a local endo support group to get in touch with you.
It is a very common condition. Or perhaps extend the invite to those with Pcos and Adeno too. There might be quite a number of students feeling alone and isolated with their gynae problems who would love a sympathetic group of supportive students who do understand.
Do your best to look after yourself and not over do things for a few weeks yet.
e.g. returning to the gym after a lap ..is 10 weeks. to give you some idea of time frames.