I heard about this place a lot, and they operate a few branches around London. Only one is a sit-down, and reservations are hard to come by, so we decided to walk to one and do takeout, as this is what they are mostly famous for anyway. We were NOT disappointed.
One of the things you should really not do is go to a takeout place when hungry and buy stuff, because you will end up buying way too much, and spending way too much. For two and a half people, we blew probably in the $70 range – on takeout. But……. it was worth it.