I stayed at Fi's for a bit less than 7 days. Overall it was a really great experience, and I highly recommend a stay.
Both Fi and Michael were wonderful, responsive hosts. They were always available to answer all sorts of questions, and made sure we had everything we needed. At some point we had a minor issue with the bathroom (the water was draining very slowly) but they resolved it quickly once I brought it up.
The house itself is lovely: simple, clean, extra towels and pillows provided, fully appointed kitchen, eggs, milk, juice in the fridge, and croissants provided (really great after a long flight). The location was exactly what I wanted. I wanted to be in a relatively quiet area just outside central London that would still be close enough for short tube rides. The neighborhood has its own lovely shops, restaurants, and cafes to explore, and a market that was incredibly close (lifesaver!).
One thing to keep in mind is there is no AC. I realized that this is actually pretty typical (the tube lacks AC as well), and it makes sense as the weather and temperature are usually pretty mild and on the cool side especially in September. But I had the fortune of being in London during a heatwave (no sarcasm intended because I generally enjoy the warm weather), so the house was a bit on the warm side. I kept the windows closed as I didn't want to let any bugs in. Other than that, all was wonderful.
Thank you Fi and Michael for a great stay in London!