Ask HN: Looking for a web app for my organization. Or should I build my own?

I work for a school and we are wanting to transition to a new way of deciding which courses each instructor teaches.

Previously, the process was not very clear and there was one Excel document where everyone added their preferences for the courses they wanted to teach.

The new process involves the instructors having their own file or "portal" where they can go in, choose from a list of courses , choose their hours and submit them for approval. We'd also like it so each submittal by an instructor updates a main overview so that everyone can see what courses each instructor has picked.

I've been doing some web dev side projects for a few months now and I proposed I'd make a web app to do just that. I've got a bunch of it finished and it'll probably take me a few more months to get it polished.

This is a great opportunity for me to show my software skills to the school and also add this as a good side project for my resume in the future. I'm just wondering though if there are websites like what I described that would work as well?