Please can someone help. I have just put down a concrete base for my new shed. It is going to be put up next week. Approx. 20ftx5ft. I want to install a couple of double sockets and lightning. How do I take the supply out. Half of the shed is next to my house wall. Can I drill thru the wall and take a cable out from an existing socket (as a spur I suppose) to do both supply and lighting jobs? Please help asap !! Many thanks in advance.