I'm planning to add an extra socket to the ring main in our flat.
The exisiting socket is on one side of a solid wall in bedroom 1,
the intended location of the new socket will be on the other side
of the wall in bedroom 2. I've already replaced several sockets
so I know that the exisiting socket is definitely part of the ring
and not a spur.

As I intend to put the new socket into the ring main I am imagining
that the cables will have the following routing:

A. Exisiting mains cables enter exisiting socket 1
B. New mains cable (and earth) is added to go from existing socket 1
to new socket 2 (on other side of wall)
C. New cable (and earth) is used to connect new socket 2 back to
current ring main

My questions a
1. What is the best way to join the cables back together - I've read about
crimping, plastic joinning blocks, insulating tape etc. The cables will be
beind/inside the brickwork so once the sockets are screwed back on
they won't be moved etc.
2. Should I drill two distinct holes though the wall for the cables
mentioned
in points B and C? or is it safe to have them next to one another? - I guess
they are insulated so it's probably ok?

If the above is too complex I'll resort to disconnecting socket 1 and
connecting the exisiting wires to the new socket 2 instead. The exisiting
socket has a 70kg wardrobe in front of it so I can't get to it.

Many thanks.
Fiona