I had a very satisfying weekend in London and the good communication with Tatiana also contributed to that.
The accommodation is very quiet and within walking distance to both a subway and a bus stop in the basement of a house with its own entrance. Grocery and breakfast options are also nearby.
The equipment is as described, clean and simple. I slept better on the couch folded down into a bed than in some hotel beds that were much too soft.
Tatiana herself values quiet, so only the creak of some floorboards was heard very rarely when she was walking around her apartment. She was responsive to individual requests and was willing to accommodate them to make my stay as comfortable as possible. (Thanks again for your offer, Tatiana!)
If I need accommodation for a weekend in London again, I will check if Tatiana's accommodation is available.