Well as I can't edit my post I'll update it as I have answered my own question about the 'wooden' trim in front of the HVAC panel in the rear console.
Turns out it wasn't really wood after all but mainly a piece of cast aluminium with a wood finish applied to the top! Looks like part number 4H0 886 745 NV4 CZ if anybody is interested.
Seems like I won't be able to cut/Dremel or otherwise modify it and it will have to be replaced along with both wooden (aluminium/plastic?) left & right side cheeks so not going to be cheap if I am even able to obtain them in Audi Exclusive Poplar Brown/Silver finish with cut-outs for RSE MMI Console?
A visit to a friendly TPS (if they even exist any more) or specialised A8 Breakers could be in order...
Still interested in how to remove the backs of the rear seats and while I'm at it the lower front seat plastic trim as I want to fit a fire extinguisher there!
Thanks & kind regards,
-=Glyn=-