Staying in Grace's house was a joy because Grace is a lovely, internationally minded host and her house is very quiet (located on a quiet street; we were staying in the double room upstairs), comfortable and clean. We were given the freedom to come and go as we pleased. Wonderful breakfast – at the disposal of the guests in the fridge were eggs, ham, various fruitjuices, cereals, yoghurt, etc etc. Nice to be able to cook something at night as well. We were even given the use of the salon if we wanted, which we didn't because London has so much to offer, but the thought was lovely. (I myself forgot to ask, but if you want to use internet, be sure to bring a laptop.)
An ample 5 minutes walk from tube station Brent Cross (about 25 minutes from tube Leicester Square), and from a huge Tesco supermarket (good and well priced) that is almost continuously open (to be reached via a tunnel under the motorway). We didn't try the bus connections in the neighbourhood but to our knowledge they are plenty and there might even be a night service.
Hop off some time at tube Hampstead – very recommendable neighbourhood with a 'Charles Dickens' atmosphere in the sidestreets and beautiful historic properties which seem unchanged for centuries, pubs (Holly Bush). Also Hampstead Heath (woods and fields) nearby for a nice, wholesome walk.