I'm a radio presenter and everyone in my line of work is self employed. The companies want it that way so they can hire and fire at will and pay no contributions. Some guys operate as VAT registered limited companies and take a dividend, others are simply sole traders. We're no different to anyone else really - I have a boss, a permanent place of work and even though freelancing outside of my main contractor is permitted by the terms of self employment it's actually rather frowned on and might end up in the media equivalent of a tea and no biccies meeting.