As above, it will depend on which engine.
The 1.2 petrol should not need the flywheel changed, unless the clutch is allowed to wear to its rivets and damage the flywheel.
The diesel has probably got a dual-mass flywheel, and these can get loose and rattly, and do fail. Then you need a new one, or have it welded up and balanced. Although a welded one will remove the vibration damping characteristics, so could in theory lead to stuff failing due to vibration.
Don't know about the twinair, but is it is a solid flywheel, should last teh life of the car, if dual-mass, same as diesel.