Rottweiler - the short answer to your question is that training costs money so the civilian SAR guys do less of it than we do. They have a lot of experience to draw on but that is only sustainable when there is a constant outflow of ex mil guys into civsar.
SARH will be more expensive than the current civsar contract because all the training burden will fall to the contractor and there will be more training required to cater for the increase in night overland SAROPs requiring NVG capability.
As for aircraft - the 139 still does not have a night autohover capability which, coupled with the contractor's decision to equip both English Channel bases with them, means the nearest aircraft are Chivenor, Wattisham or France to cover one of the busiest waterways in the world. But it's OK it's cheap
