That sounds great there's no better way to break from uni then to plan a holiday away!
As a Brisbane local myself, I could list a handful of great things to do in the city including visiting Lone Pine Koala Sanctuary, Rock Climbing the Kangaroo Point Cliffs or cycling around the city.
However, as you're looking for day trip options my top picks are Moreton Island, the Sunshine Coast, Gold Coast and Byron Bay. Yes, all obvious choices, but there is a wide range of tours and activities you can do in each region such as scenic tours, cruises, surf lessons, kayaking tours, snorkelling adventures and more!
You can check out one of my recent content articles: Top 5 Long Weekend Getaways from Brisbane, for some inspiration.
I hope this helps! Have a wonderful time and a great break from uni!