I would think 3 to 3.5 hrs labour ....around £50 to £60 an hour plus the parts....spring around £25, boot kits around £9 each for good after market parts and around £30 for the cables....a good mobile mechanic will be your cheapest, but make sure he is known and reliable. I am an mot tester, by the way ;-).
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix caravans/motorhomes.