Writing Radio Sitcom
Just completed one. Well more of a play really in the comedy/drama vein. It's a good way in. Best get in touch with your local radio stations. As part of their remit they often have to show they're developing local talent. They usually will have a link to a theatre company (usually amateur) who are providing them various things.
I originally sent my script for a stage play to the said theatre company and they asked me to adapt it. So it's a possibility to get your stuff out there. Don't expect to be paid though unless the station gets a sponsor for your stuff or a large number of stations option your work. Better than it sitting on a computer doing bugger all!