The Chipmunk is no problem for a motivated an-initio student. We've had 3 in the past 4 years; two middle-aged and one teenager. The teenager soloed at 16, so it can't be that difficult.
It does have a low crosswind limit (10 knots) but in military service it was 15 so the aeroplane is well inside its comfort zone in civvy life.
It's bloody cold for the instructor in winter though....