I would highly (!) recommend staying at Andrea's. The place was really nice and clean, we had a comfortable bed and provided breakfast. We felt like staying at my aunt's. Andrea is a super host, she helped us with many issues (where to go in London, how to get there ... and many more tips) and she is fun to talk with, she tries to make your stay as pleasant as possible.
Of course the accommodation is not in central London, but in around 30 min you are where you want to be.
If you go to London, I would definitely check first if this place is available. Cheers.