The barn is all bare floorboards and I want to cover it in the bedroom with Carpets - didn't even mention that as thought it wouldn't be an issue.
It won't be an issue, unless these are old boards (unlikely in a conversion, I imagine) and your carpet is somehow going to damage them.
Fundamentally, do you like the idea of living in a historically-significant old building?
If the answer is no, don’t buy it.
I have a few neighbours who act as if it’s a terrible inconvenience to live in a 370-year-old building, and I think “so why on earth did you buy it?”.