It's possible that someone else has posted this before but I've just come across it and thought it may be helpful for those of you moving from the UK.

This is the Inland Revenue's mini-guide/basic information for what you have to do re: tax and telling them when leaving the UK. It's actually mostly comprehensible as well, which is handy.

http://www.hmrc.gov.uk/incometax/tax-leave-uk.htm