How much SAR experience to [sic] military winch ops and winchmen have when they
first go on operations?
Good point - except that a brand new RadOp or Winchman will be crewed with a much more experienced Winchman or RadOp while the new guy is Limited Combat Ready (RAF practice - no doubt the RN do something similar). And with the generous amount of training available, the new guys gain experience very quickly!