Hi Jem
I confess I haven't watched Monarch of the Glen. I've just looked it u and came up with
Ardverikie Estate. There is a picture that looks a bit like a castle there - is that the building you mean?
The Sazburgh castle sounds wonderful. I live near Cawdor Castle which is a building which is lived in with what looks like a sound structure. I enjoy ruined castles and find they often have amazing energy, for instance
Montgomery Castle in Wales and
Kenilworth Castle in Warwickshire, England. I have also visited Warwirk Castle - well worth a visit if you get the chance.