GA in the Chipmunk I would not initially reduce flap until the aeroplane is climbing and airspeed is good. Touch & go however, I'd reduce to 'flaps 1' from 'flaps 2' on the roll, tail up, (having put full power on first) which involves an interesting but by no means difficult change of hands on the stick so the right hand can operate the flap lever.
The only thing I'm not happy about with this is that the there is no free hand to keep on the throttle for the second or so it takes to do this. Would add that I generally operated out of quite short grass fields.