Thanks everyone for you input much appreciated. So was on site again today and it would be a much bigger job to hook up to CU as there would be 40 slabs to remove instead of 4. Agreed LED lighting for sure. Got as far as FCU house side from ring main to 2.5 twin&earth in trunking put down under slabs with warning tape to garage (6m total cable length) . But in the garage I would like to go connect to an RCD and from RCD split to lighting FCU and the other straight to mains sockets. Or would you advise a mini CU with RCD and 2 MCB's? Thanks for your help.