You also need to decide where you will site the RCD. In this
circumstance at the head end of the supply would probably be acceptable.
Depending on the earthing system in user you may or may not have a choice.

Thanks for you comments,

I was going to site the RCD where I change from TC&E to the Armoured
Cable is this not suitable. Do I need to run a separate earth cable
will the one in the TC&E nor suffice?

Cheers,

James