Don't know what to doWatch
There's no guarantee about who you could meet at uni and what your flatmates will be like. Hopefully you'll enjoy the course you're going on.
I used to feel similar to you. But after some therapy (which really helped my self-esteem) and a change in my environment, I no longer have those same worries about making friends or not there, or what my flatmates will be like. It'll get better, but it will help if you see the positives in you and believe that too. Take some chances, even if it's baby steps, and you should find your footing and put those worries to rest