You've got to somehow distil your whole idea into just 140 characters (which admittedly might be a bit of a flawed way of pitching)... but the prize makes it worth giving a go I think: a ticket to the Broadcast Comedy Forum where you can mingle with the top producers and things (tickets to the conference cost over £300 so probably the only possible route in for many)...
https://www.comedy.co.uk/news/story/00000346/broadcast_comedy_forum_pitching_competition/