So, I've applied to the Writers' Guild of Great Britain for student membership. All you need is twenty quid and a letter from the college at which you're studying that proves you're undertaking significant, academic studies in screenwriting. Napier University kindly supplied the letter and my overdraft did the rest.
Organisations like the WGGB make important breakthroughs that benefit the careers of all writers, not just members, such as negotiating minimum terms and conditions with massive corporations like the BBC. (The Society of Authors does similar good work on behalf of published writers. By comparison, the Crime Writers' Association is more of a social animal.) I believe unions and guilds are a good thing. If you're a writer, support your guild - it supports you! End of sermon.