Yes, I guess I am lucky as you say. Downside is that insulating it is going to take longer, cost more...etc. but it should be worth it.
I'm dead envious of your wood burners. Wondering how I can swing a similar stunt myself now... I'll think on that for later.

One garage door is now completely insulated. Looking like a silver space-ship hull from the inside now.

A shed-load of rigid insulation board arrived today on the back of a lorry... destined for the garage roof. Weekend activities blanked out as a result.

I put some spare lino on some batten planks so that lino overlaps about 2", and mounted them above the garage up-and-over doors. The flap of lino brushes the top of the door, and forms a neat draught excluder. Works a treat. Thanks for the suggestion Mocha.