(NB: this is not 'advice'. It's what I personally found to be helpful. It's also far from exhaustive. There's loads out there. Use what works, bin the rest)
1. Scriptnotes-The granddaddy of screenwriting podcasts. Writers John August & Craig Mazin plus loads of special guests take you through every aspect of writing for film & TV. There's over 400 episodes so pace yourself scriptnotes.net/#
Now, on to...
1. @bbcwritersroom Script Library - This massive library of scripts provides endless reading opportunities & includes some of the BBC's biggest shows. Sherlock, Line of Duty, Happy Valley-all in there bbc.co.uk/writersroom/sc…
(There are lots of university screenwriting courses & paid training/mentoring out there. Here I'm going to stick to the free/less obvious stuff).
Contests can often promise a lot. And can often charge a lot. And often you'll wonder why. Some are scams. Be careful, be ready, be sure. With that proviso, the contests I've found to be genuinely helpful/worthwhile are...
Channel 4 Screenwriting course - free again, excellent track record (script-consultant.co.uk/channel-4-scri…)
Edinburgh TV Fest New Voices Award - affordable entry, great people (thetvfestival.com/talent-schemes…)
Getting people in the industry to read your scripts is hard. Many people don't read unsolicited submissions and there are good reasons for this. Respect them. Helpfully, Phil Gladwin's Screenwriting Goldmine site produces an annual booklet...