Get your paperwork in order and shred any documents you're not going to move with you.
Check your credit file online to see what information is held about you.
Inform lenders of any unused credit facilities that can be closed.
Check for old catalogues you've used to buy things in the past and inform the supplier that you are moving.
When you get to your new home, register on the Electoral Roll at your new address immediately.
Make a list of every financial company you deal with and inform them of your change of your address.
Contact the Royal Mail and arrange for your mail to be re-directed to your new address for a year. This will also give you a chance to cancel anything you don't want and send your new address to anyone you have forgotten.
Consider registering free with the Mailing Preference Service. They will ensure your name is removed from direct marketing lists at your previous address.