Worth a read for the Brits...

https://www.screenwritinggoldmine.com/how-to-become-a-screenwriter/

A good article there with some interesting links.

I think for me, the problem is very much time. Writing is essentially a hobby which takes up what little spare time I have. This leaves nothing really for promoting my work, trying to get it noticed, optioned etc. My day job and family take up most of my day and my job pays way more than I could potentially earn as a writer.  So for now, I’ll just have to continue writing for my own personal gratification, get involved in the odd competition and movie production and see what happens as it happens.

I've got exactly the same issue re current career, family etc, but I've managed to create additional time for the marketing stuff by not sleeping, down to approx 4 hours a day ;-)