Hiya IrritableBob! I'm in my first year of university and I've had Crohn's for almost 10 years, so I hope I'll be able to help a little bit here.
First of all, it's SO important to make sure your condition is known to your university's disability services. They don't have to tell all your lecturers/tutors if you don't want them to, but it's massively important so that they know if you need to take a lot of absences, need an extension on an assignment, or need any adjustments, such as toilet breaks in exams. They can also help with the process of securing you a room on-campus, or with its own bathroom, if that's possible. There's so much they can help with!
I think secondly the main advice I'd give is to allow yourself some healing time, especially if you're flaring. There'll be times when you can't do what everyone else is doing, and it'll be frustrating, but pushing yourself harder and harder just leads to things getting even worse (as I'm now experiencing). This ties into not getting too stressed, too. Stress just ruins everything, for no good reason!
I think the final general thing I'd say, though, is that you should enjoy yourself! There's so much excitement in transitioning to university life (I joke with my parents that it's like a tutorial level for adulthood) that sometimes it can feel really overwhelming, but the most important thing is that you're enjoying yourself. There's so much support out there if you need it, so feel free to have some fun!
I hope this helped a little! Please let me know if you have any specific questions and I'll do my best to answer them