Hi all - dd now in 3rd year but I sympathise with the anxiety around freshers week.
There was quite a lot of turnover in the self catering flat dd was in in first year. Only 2 of the original 5 were in the flat at the end of the year and dd found her friends in the girls and 1 boy in the flat upstairs , the "rugby boys " in the flat downstairs, on her course and through activities. In second year she shared with 3 of the "girls from upstairs" and is planning next year to share with the other girl who was left in her flat. This year she is in private halls as the only girl in a flat with 3 boys.
Interestingly dd found last year it was one of the girls who was messiest while random boy allocated to their flat was almost compulsively tidy.
it does take a while to settle down and for them to find their feet - I think all you can do is be at the end of the phone and assure them that everyone else is struggling to find their way also - some are just much better at putting on a brave face .
It is worrying for parents and so hard to see your young person struggle so hugs to all who feel in need of one.