Do you have any particular insight on where Westeros might get its coal? Its mentioned in passing in multiple books, so we know they have it, but I’ve yet to come across any accounts of where they might be getting it from.

Coal, at least in pre-industrial quantities, is probably ubiquitous enough that it doesn’t come from one place in particular. We’ve got coal being used at the Wall, in the Westerlands, in King’s Landing, in Essos, etc. 

Peat is less commonly used, and seems to be used only in parts of the Riverlands, parts of the Vale, and parts of the North.