Hi!
I'm a current student at Essex so hopefully I'll be able to help. I love the nightlife here. On campus we have the SU Bar which hosts our karaoke and cheesy music night, Milk It. It's great for reliving your childhood! We also Base Bar and Club which hosts nights specific to certain genres like grime or rock and indie. Then there's our club, Sub Zero. It has Sports Fed on a Wednesday where all the sports teams go out in costume but everyone is welcome, then there's the Friday Night Project which is like chart music with a few others thrown in. Saturdays, there's often a special guest, in the past we've had Zane Lowe and Hannah Wants. Outside of campus though there are some good bars in Colchester town if you're into more live music nights. There's also the new club Atik, I haven't been but I have heard good things.
Don't hesitate to ask if you have anymore questions!