As you're using sheathed cable (T/E) protected by the MCB in the CU, then you can have the cable btween the CU and your RCD enclosure as long as you need.
I assume that the shower rating/cable rating/MCB rating all tie up?
As for the earth, yes - use a connector block (fixed down) in the mini-enclosure, unless you can get hold of a DIN rail mounted terminal block (like one of these
they are available in some of the larger B&Qs...
I assume that the shower rating/cable rating/MCB rating all tie up?
As for the earth, yes - use a connector block (fixed down) in the mini-enclosure, unless you can get hold of a DIN rail mounted terminal block (like one of these
they are available in some of the larger B&Qs...