Work experience for TV/FILM - PR consultant wants career move

I'm a PR consultant wanting to make the move into TV/film production (ideally looking for a pre-production role like a runner or researcher).

I have student film experience and obviously transferable skills in terms of research/current affairs etc. But otherwise, I need to get some work experience on my CV!

Can you give me advice as to where to look for work experience and how to shape my CV for this? I'm interested in TV & Film. Thanks!