Sounds peculiar...

Supposing - not entirely hypothetically - I wanted to get involved in sound design for radio/audio drama...what's the best way to go about it? I'd love to get involved with an organisation like Big Finish, but I don't have any demo material to send them, 'cos I don't know anyone who's recording audio drama that I could use to do a sample dialogue edit to send them...seems like a bit of a vicious circle...