The Chipmunk Club published a short list of places where you could train on or hire a Chipmunk in their April 2001 Newsletter.
It said the information was correct at January 2001.
Two in Lincolnshire were mentioned, which are probably closest to you, they were....
Fenland Aero Club 01406 540461, and
Wickenby Aero Club 01673 885345.
Geographicaly, the other places mentioned were....
Channel Islands....Jersey Aero Club
Bucks...Wycombe..BA Flying Club
Devon...Eaglescott..Devon Airsports
London...Elstree...John Schooling
Merseyside...Liverpool...Liverpool Flying Club
Wales...Hawarden...Chester Flying Club.
Comed at Blackpool also mentioned but I think they're no longer operating?
WF.