Beefer,
The point is not one of rotation of crews it is that ALL RN rotary crews are SAR capable and on standby when embarked.
Re "theoretical" deployability of the UK SAR Force - the point here is that there is no deployable role for the RAF SAR Force, the RN SAR a/c can and do deploy to the CVS for SAR/HDS duties.
Re Civ SAR - there is no reason why the CAA could not clear Civ SAR to the same limits as the current Mil SAR to allow overland SAR - the police are already NVG cleared etc.