I stayed in Marianne's spare room for 10 days, and the experience was really good. The room was super clean, as was the rest of the house. Room is fairly small, bed is somewhere between a large single and a small double, would probably be pretty tight for two people. The house was very quiet, the room had lots of natural light, and there's a lovely garden.
I worked from home several days while I stayed - there was a good space to work from in the room and the wifi was decent. Marianne was there as well on most days, but she was very respectful of my space and my privacy; she was interested to have a chat and a lovely person, but not at all intrusive. Helped me feel very comfortable and welcome in her house. That's great because it's a fairly small space so you see plenty of each other if you're not in your room all the time.
Marianne left me cereal for breakfasts, plus coffee and tea, gave me a shelf in the fridge and I used the kitchen to make lunch a few times as well, plus I was able to use the washing machine as well. Marianne was very helpful and keen to ensure I had everything I needed.
The area is good, very close to Brockwell park, a short bus ride from Herne Hill or Brixton, and there's a good group of pubs, cafes and restaurants, as well as a supermarket just down by Tulse Hill rail station which is about a 5min walk.
All in all it was a very good stay and I would certainly recommend it to others.