Depends which material you pick as insulation. There's synthetic and natural stuff that both claim to be breathable. Picking an installer with half a brain so that they don't fuck it up somehow will be 80% of the battle on that I reckon.
yeah lol, basically the only reason we haven't done much on the house yet is that I dont trust anyone to do anything competently and having to pay even more to reverse what's been done.
also victorian end of terrace here
Would the plan be to remove the existing render? Is the new external insulation breathable?