There are various 'trusts' in the UK who rent out properties that are well worth looking at RichardinSF. The Vivat Trust is one of them. I have rented The Tower of Hallbar, also known as Braidwood Castle from them. For some reason I can't seem to get the page up on Vivat's own website but here is another website that rents it for them as well and has some good photos.
https://www.lhhscotland.com/properties/detail/?id=25690
People often don't think outside the box when it comes to places to stay. Universities for example often rent out student accommodation when 'school is out'. Imagine having stayed one week in each of two years, being able to say to some pretentious bore at a cocktail party, 'oh yes, I was resident at Oxford University in 2018 and in 2019. I enjoyed my time spent there.' Not a lie exactly but definitely misleading. LOL
https://www.universityrooms.com/en-GB/city/oxford/home