Here are some links - divided into various categories:
Double or Quit race website
Local Clubs:
Heanor Running Club
Long Eaton Running Club
Mansfield Harriers
Chesapeake RC
Kimberley & District Striders
Ripley RC
Wirksworth
Associations:
UK Athletics
North of England Athletics Association
Fell Running Association
General Running websites:
http://www.therunningbug.co.uk/
Runners World
Brian Mackenzie's Site - a great source for all manner of running and training information from a level 4 coach!
Retail & Commercial websites:
Derby Runner
Team Link Sports Tours - they are organising a trip to the Malta half & full marathon in Feb 2010 - See Nat Lebeter for more info.