One thing I did forget to mention - having just been playing in the shed and, in the light of this thread ('scuse the pun) glanced up at the CCU - when running cables to and from the CCU in a shed or garage where there is a risk of condensation, run the cable up to it and, if bringing cables in from above, leave enough to put a 'U' in the cable so that you are always bringing the cable up to the point of entry in to the CCU.Thanks. Very helpful and reassuring.
Yes, 2.5mm twin and earth for the sockets and 1.5mm for the lighting. Using a CCU with a double pole RCD and a single pole MCB (rated 16A) for all circuits at the mo. When funds permit, I'll change this for one with two mcbs. I see they're quite reasonably priced on Amazon.