At the moment the BBC is running a short story competition for kids 13 and under. Enter and you could win Chris Evans’ height in books plus 500 books for your school library!
Information can be found on the Radio 2 website here: http://www.bbc.co.uk/radio2/500words/2013/
If you’re a young writer I’d really recommend submitting your story! The deadline is 22nd February 2013.