Here's a revised (and clearer!) version of my turnout wiring diagram. I realised that only the frog/crossing itself need actually be switched, not the rails beyond the turnout.
The blue line represents the wire/rails that will be switched depending on the way the turnout is set. The brown colour represents the copper-clad strips: one piece connecting the rails of the crossing, and one connecting the switch/closure rail with the adjacent stock rail (no need for multiple copper-clad strips at each location is there?).
Insulated rail joints are shown in black - all other rail joints will be represented cosmeticly.
Rather than trying to pass the dropper wires up through the sleepers/copper-clad, solder on top and file flat (which I tried and found that filing the joint flat basically removes the joint!!), the wires will come up immediately adjacent to the timber/copper-clad and be bent over and soldered on top of the copper-clad where it protrudes slightly from beneath the rail. (This will be on the non-viewing side of the rail to hide it from view, and further disguised with the general dirt, grass and weeds that will encroach on much of the trackwork anyway).