As to capacitive and inductive linking it is hard to separate the two when looking at cables, we all know the problems when putting cables through different holes in a ferrous box.
Yes I do tuned circuits etc, but not really worried in this case if capacitive or inductive, AC can leak, don't need to go further.
@spike47 seemed to imply he was not doing the work, only gathering info and materials, now he shows a box well known for asbestos pads, yet another problem, I know we can ignore it, and many do, but if as he says some one else is doing the wiring, it is likely they will not. If he is not getting some one else to wire it then clearly he can do what ever he likes, even use knife switches with exposed live parts, should some on die as a result then likely HSE will visit and we would read the court case, but unless some one is injured no one would know.
Because I worried about my family and fitted RCD's back in 1993 does not mean everyone worries about their family, some may want to get rid of their wife, from pictures I would say sell sun bed and make the home safe to live in with the money you get for it, but I love my wife, and don't want to see her go, so may be you have different priorities.