Brendan, a fellow Birmingham screenwriter, told me about Mandy.com and their writers wanted ads. You can visit it each day and search or you can create a specific RSS feed for your reader.
If you use Google Reader this feed gives you all the UK screenwriting jobs.
Also via the Screenwriters Festival site is this ad:
Screenwriter sought: Paid vacancy!
New Me TV is launching an information and entertainment website for girls aged 13-24, and will produce a web tv drama series that will contain part-reality including production meetings, interviews with the girls, and make up session. The entire series will be 60x3 minutes with 20 episodes of reality and 40 episodes of drama. The synopsis is about 5 girls competing to be the face of Covergirl Magazine, the leading fashion magazine. During the competition, factors come into play including relationships, university family and tragedy. We are auditioning the girls on Saturday at Bluewater with the launch of the website.We are looking for a young but experienced writer to work with us on the script of the drama. The position would start with immediate effect after interviewing and is well paid. Please send through your cv and contact details to Mary Booth at firstname.lastname@example.org. We look forward to hearing from you!