The loom passes through the "kidney bean" shaped hole on the left, the same as on the US model but I think the loom is slightly longer in the under dash area to reach the gauges on the right side. I used all US looms on my car but had Vintage Wiring Harness in Australia manufacture me the dash to engine bay loom as per RHD specs as a US one was too short. The harness to the taillights runs down the left side of the rails and hooks up with the loom that comes out of the kidney bean hole. The only different thing to the US LHD wiring setup is that aforementioned elongated dash loom. You could probably have a US manufactured one extended or see if the respected Tyree Harris who the Yankie boys rave about on this site, will do you a custom job....Where are you? (you don't say where Watership Down is on your profile, I take it you're not a rabbit)
That dashboard trim is hard to get. You could get it in Chrome diecast metal ( without the clock) or plastic in 2 parts ( with clock hole on the glove box side). I suggest you try to repair it (I presume it is the plastic) with an epoxy type glue and paint it as near colour you can get.
Hope this helps. PM or e-mail me if you want any further help as to routing the wires, I've done 2 of these 46/48 Fords which basically had the same wiring setup as the 41.
Also all our 46/48 Fords carried the 41 US strip styled instrument panel.
GB
PS : I'll double check on what side of the chassis the loom to the tail lights run down in the morning. It's pissing down outside at the moment and the garage is detached from my house.