Hey! I totally understand, I’ve always been really anxious especially socially. I did my degree 2012-16 and I’m going back to uni in September too. I was SO anxious before I went and in the first few weeks but everything worked out fine.
I joined some online groups before starting too but honestly I didn’t find it that useful, I think it’s quite hard to get to know people online and make friends that way. Just like anywhere else people can be rude or difficult, but I found uni much better in terms of bullying etc mostly because everyone has chosen to be there doing that course. I made really good friends on my course, I’m still close to them now!
My advice really is to be yourself and try and push yourself. Join societies, go to events, do things you find scary. But also take care of yourself and know when it’s too much. Also remember everyone is anxious about something when they start uni, some people are just really good at not showing it. Good luck, you’ll do great!