Christ Church Park is one of the main parks there and they hold events throughout the year, a couple of shoutouts are music in the park (which might have been renamed now) but there had 6 stages last year and the Indian summer mela (The food is AMAZING!).
There are also a bunch on restaurants and bars in the town which are targeted to students/younger people. Felixstowe is super close if you want to go to the beach and get some chips and London isn't far by train as well.