The Chipmunk is fairly well supported in the U.K spares wise with a number of stockists for the major items. Items which are causing concern are fuel tanks and tailplane support tubes and I guess the likelyhood is that a batch of both will be made in the next few years.
It's critical to have someone check the paperwork reflects the actual aircraft and to make sure that the fatigue calculations
are correct. If you wish for any more information please contact me.