University and Winterfest

Nothing. Holidays do not impact University, so you need to make sure you still send your Sims to any classes they have on the Holiday.
The setting for "no work/school" for a holiday doesn't effect University, only grade school and high school.

I found out you don't need a cheat to add a tree to the library/cafeteria building in Britechester-U. I have my students go there after classes on the holiday so they can also have a holiday meal, too. For free. :) Since I generally have taken seven students through uni together, I have some of them set the two long tables for the Feast Day. One time they graduated and left the campus on the Eve of the holiday and I had them all move in together in a very large castle. So they didn't have an 'awful' holiday.

@BeorgeAarg61 Yes, Father Winter does show up. As for gifts I add two large piles of them ahead of time. That way any dorm-mates can also open a gift.