Wiring kitchen ring query when kitchen part installed
 

We're planning a new kitchen ring, and a problem is that part of the
kitchen units are in place and essentially are immovable. The kitchen
work area is U shaped, and chasing the start of the ring should be no
problem, going up from the floor to a first socket behind a cupboard
adjacent to a built in appliance, and accessible for control through
the rear of the adjacent cupboard. Then up to the first worktop
socket, and horizontally for 3 double sockets on one side of the U,
following round to a 4th socket on the next part of the U. i.e.
_________________________
| +4
|+3
|
|+2
|
|+1
|

The + are worktop sockets. The problem we see is chasing from socket 4
to continue the ring, as that part of the kitchen is immovable. The
ring can be continued by chasing down to below the worktop, but the
cable cannot be chased into the wall just below the worktop as the
wall is inaccessible. There is a gap currently between worktop and
wall, so the cable can physically be run between the wall and back of
cupboards. We're wondering whether it is permissible for a cable to
emerge from the wall in what will become a concealed point, and for it
to be chased back into the wall at another point? Of course it's not
ideal cosmetically, but it'll be invisble.

Another question is wiring an extractor that will be located to the
right of socket 4. If 4 does not end up as a spur, then can the
extracter be powered as a spur from socket 4, e.g. by running
horizontally from 4 and then vertically to the point where the cable
emerges? Also, are extractors usually plugged in to a socket that is
hidden (e.g. behind the flue), or wired without a plug into a surface
box?

Following the ring further round the kitchen is also a problem, but
hopefully solvable. There is a radial for a fridge freezer on the
opposite side of the kitchen, but presumably that cannot be extended
to power one or two worktop sockets on that side of the kitchen, and
all worktop sockets should be on the ring.

Guidance very welcome on this.

jc.