artyjools I can totally understand why you walked away when that was the stance of the VOA. The one I dealt with meant they had 2 kitchens but removed one because it was on the top floor of the house and removed the external stairs so had no way to access the "flat" without going through the main house.
They reinstated the bathroom later on, but made it uninhabitable to get the class A exemption.
To be honest, as we all know Council Tax was rushed through and there are times when certain situations arise and we would make a "local precedent."
We had part of a road that flooded. This occurred very quickly and in the middle of the night so people left their homes with what they could carry. Technically to get a class A exemption the property has to be empty and unfurnished.
When we visited the properties to confirm this, the entire downstairs had to have the plaster removed, new floor joists, electrics, and a new staircase as it was wooden and dangerous.
But the family had left behind several large, heavy free-standing wardrobes as there was no way you would risk bringing those down the rotten stairs.
So despite being "furnished" we gave it a class A and set the precedent for any future flooded properties in our area.
MyLovelyMonster if you do go for it, never mention anyone staying in the "annexe" it is part of your house, you use it daily (kid's chill room) and the other room is an office, the kitchen is now the utility/laundry room and you can show this by staging it all, add the things that demonstrate the identity of the room.
The VOA are often proved wrong with banding etc. Personally I would fight them tooth and nail.
Good luck.