Thanks all. So my plan is OK but not ideal, I didn't see any major
objections. The problem I have is that I cannot get to the CU without
ripping up loads of floor boards and drilling holes in joists, the
radial option too would of been my ideal setup.
Now onto the bonding bit, what is it exactly I will need to do? What's
equipotential bonding as opposed to double bonding? looking in my other
bathroom I dont see any earthing at all on the copper. Do I need to
earth my towel rail, or the pipes going to it? I guess if there is an
earth somewhere on the copper this will be OK??

Thanks for your help as usual

Cheers

Richard