Aparthotel offers a small, nicely designed room. The room is clean and there is a separation between the bed and a small living area with a kitchenette. The staff is very pleasant and helpful. Groceries are nearby, as well as tube stations. It's an affordable option in an expensive city.
Be forewarned that some rooms lack air conditioning. Considering the climate in London, that should not be a problem for much of the year. We experienced a few warmer days in October. The room was stuffy, and we had to open windows to sleep comfortably.