I'm a mature student under Social Sciences 1 so I'm limited with the amounts of units I can take per term for my first year. Currently I've maxed that out but I have a lot of 4+ hour gaps on my schedule where i'll be on campus with nothing to do. I've tried rearranging the courses with different times but no matter what there will be big gaps. I'm trying to find non credit courses to fill those gaps (similar to SOCSCI1EL0, Introduction to University Through Experiential Learning) but so far I haven't found anything yet. Any advice on similar courses would be very appreciated!

There are very few courses with no weight (worth 0 units), since these are usually just a few hours of class to fulfill some sort of requirement. You won't have any luck if you're looking for more of them.

The most you can do is either see if you can get permission to take extra courses, or switch your courses around - you'd have to decide if it's more important to you to take the courses you want or get the schedule that you want.