hey, 2021 4u english student here and i wanted to add some stuff about doing a short film -> i had thought of doing one - keyword "thought" and the head teacher literally tried to bully me out of it - and some of the concerns they raised was true - a short film can be incredibly difficult to make as its hard to make changes immediately, you would have to amend the script, grab your actors and recreate the set to ensure continuity, while for all other forms its just opening a word document. Also, a lot of teachers are not equipped with knowledge on film or film production, so they would be not very helpful, which is not ideal.. of course, if you believe you are capable with the film medium, do go ahead with your vision, but your 4u process will be quite different to someone just writing a short story.
at the end, i went into the 12 year with a different idea, and found that a short story/script hybrid suited what i wanted to do better + i was still able to incorporate aspects of "film" into my script - so what to get from this is to really think about what form you want to choose and your ability to create in that form, esp in your busy yr 12 year.
also, for inspiration, of course you can talk about movies, tv shows, anime etc, I choose the hannibal tv script as heavy inspiration - HOWEVER you should find pieces in your form, i.e short film to write about in your internals and external reflection. so start binging and reading the scripts of as many short films as you can