Olivia's place is great. She really is a kind and welcoming host. Me and my wife stayed there for a few days. There is a 1 full size bed (very comfortable!), a bath, great WiFi and so much more.
The location is quite good. It's not central London, but the overground is 2 minutes walk for the flat. There are also buses nearby, so public transport is great and you do feel in the center of things.
We personally did not travel in the vicinity of the flat even though it's cool, but everything was a short drive by train, so it was not a problem.
There are excellent places to eat nearby, supermarket right across the street, and a large supermarket in a shopping center 2 minutes from the flat.
We had a great time. I strongly recommend Olivia's place.