Hi! I'm a third year Swansea Psychology student! I personally would recommend looking for accommodation on the campus that you will be studying on. The bus rides to campus each day, although they aren't that long will be taking time out of your day, and a few of my friends who lived on Bay campus but studied on Singleton did not enjoy getting up earlier than they needed to for a 9am lecture!
With regards to the social side, Singleton campus does tend to hold a lot of the bigger events such as freshers events, and summer ball, with a weekly club night on a Friday called 'Tooters', but Bay campus does also have social areas too such as the bar Tafarn Tawe, along with many sports facilities on Bay campus. People I know who lived on Bay certainly didn't feel like they lacked a social life, so I would not be concerned about that living on either campus.
Hope this helps!
Abbey