There arent many rooms at riseholme, you will find that there are more people coming in from the main campus than actually staying at riseholme
yes for the first week they may stick together as they will have got to know each other in halls but its not a massive proportion so i wouldnt be concerned.
This is from the view of a third year who is staying and has stayed every year at riseholme.
Theres a little bit of a divide but not for long, I talk to many people that live off campus
hope that helps :-)