Had to sign up for this. Take extra care to use appropriate materials for a house this age or you'll create more problems than you solve. Solid stone walls need to breathe!

Make sure you've spoken with a surveyor specialising in heritage property too.

PIR boards are almost certainly unsuitable.

https://www.victorian-house.co.uk/ (be sure to pick up a copy of the Haynes Victorian House manual, it's a gem)

https://www.lime.org.uk/community/boards-insulation.html

I'm currently having to undo poor choices of modernisation on a building of the same age, which caused tremendous problems with damp.

Another good resource is https://www.neighbourhoodconstruction.org e.g their page on Thermal Envelope > Bio aggregate https://www.neighbourhoodconstruction.org/bio-aggregate/

Thanks for taking the time to sign up.

I intend to use rockwool for the floor and roof crawl space.

Luckily I have a relative in the field who can share advice. I am conscientious of the condensation issue. There's a company local to me who use hemp boards which are porous. What you say is definitely something to consider given the extent of work involved, and to possibly undo.