not sure which Uni you are going to and how important flat mates are in terms of context...
So much goes on at Uni at the start, on rare occasions people you meet or share accommodation with in first days can be the most significant in friendship groups but usually things do not turn out this way and more often people you share accommodation with in first days, quickly fall from all radars.
Often this happens in a way you do not anticipate. So for example, you meet person A and think, 'oh great etc " and hardly notice person B who turns out to be the most longstanding friend or influential friend of your life.
Personally I hate Facebook so much would dismiss anyone on it but what is it about their Facebook that made you think you did not want to go to Uni?