We have stayed here before, and in both cases checking in and out was easy.
The apartment is cosy and has all the equipment for even a longer stay (we were here a full week) - outside you have bakery, super market and cafes within a range of a few meters. The bus stop is riht outside, and down the street 2 rail and one underground station that will get you almost anywere in London within 30 minutes. If you prefer walking Hampstead High Street and the Heath is close.
Defenitely a favourite