Got a TT installation but the earth rod is in a flower bed that will
shortly be a step to the moved front door surrounded by a block paved drive.

System at present is TT via 2 overhead cables. No obvious earths down
any of the supply posts.

I have asked my supplier whether they will convert to TNC-S and am
awaiting a reply. Can anyone comment on my chances of getting the supply
changed over? EDF Energy area but my supplier is Atlantic Electricity
and Gas.

DIY bit if I have to stick with TT.
The solid porch floor needs re-tiling with another layer of ceramic
tiles on top of existing. To get an earth to an earth rod in a suitable
area it would need to cross the porch.
Can I cut a channel for the earth wire in the floor and lay conduit for
an electrician to use when the rod is moved? If so how deep does it need
to be and does it need to be covered by anything special?
Total run would be about 6 metres. How thick would the cable need to be
so I can get the right conduit.

Thanks as ever for any replies.