Is timber frame really 'non-standard'? No problem here getting a mortgage or home insurance on our timber frame. We do have a masonry outer skin though, so maybe that helps.
Ornate mouldings are not skirting boards though. Let's not forget that skirting boards fulfill the function of protecting the plaster at the wall-floor junction. My wife uses it as a bump-stop for the hoover.
If you can't see it on Google, then no. You can get standard profile pine or mdf skirting up to about 150mm, but anything above that will probably be made to order. Do you have a picture of what you're after?
I think they are generally made up from a number of separate pieces of timber and standard mouldings (quadrants, Scotia etc). I had some made to match Georgian originals.
I like glass, but maybe half of it. Dispensing with the dual aspect corner bits will simplify things and reduce structural complexity. You can still have the views, but through smaller apertures.
Welcome, and congratulations! Old buildings can be a challenge, particularly when they're listed. I assume you realise you'll need Listed Building consent before you start anything significant; best to get your plans drawn up and submitted all in one application.