This is really difficult to answer, as no matter someone's age and uni status, you can never predict what someone will be like (quiet, loud, adventurous etc).
In my experience this has been mixed. One person was relaxed and quiet, whilst the other was more outgoing. It's really a roll of the dice.
You could always look at websites such as spare room, sometimes people who live there upload a brief description of themselves to help give you a better understanding of them