I have a stud wall in my house that is 85mm uprights with 20mm lathe
and plaster each side.

I have access to the inside of this wall (at the top and bottom) at one
place along the wall, and would like to run cables down it for a ring
main. The regs say that cables must be at least 50mm deep if they are
unprotected. There is an area 25mm wide that is 50mm from each side of
the wall.

So, should I run my cables in this wall?

Would I be better off putting them close to one of the sides of the
wall and adding a socket in the same area (to turn it into a permidded
zone)?

Comments please...