First of all, Henrietta and Billy are nice and very helpful when it comes to giving general advice on London. If you're thinking about doing a short trip to London and staying quite centrally without paying a fortune, you can book one of the rooms. Transport is great in this area and supermarkets are also close by.
If you intend to stay for a longer period, however, I would not recommend staying at Henrietta's. I ended up staying for 3 weeks instead of almost 5. I got a different room than initially booked (the room I stayed in is not even listed on airbnb), the heating was not working well, the house itself is actually really nicely decorated but is not very tidy and clean. When I arrived my room was packed with personal stuff and I did not have much room for my own clothing. Also be prepared that the cleaning lady or Henrietta will eventually enter your room although you're not at home. If Henrietta sleeps in the house, she will sleep in the living room which is right next to the door. During my stay, all rooms were rented via airbnb.