We had our breakfast at the Club (of the hotel) when we were in London every day. We thought it would be easier that way, because a lot of breakfast places do not open early enough. It was also rather cold to go out, especially in the morning. We wanted little effort and in-house breakfast was our best option.
There were some items that were constantly on supply, but some changed a bit here and there. There were always vegetables and fruits with hummus and cheese as well which I was quite happy of. They had cereals, bread and pastries too. I normally tried to start with piling up fruits and veggies on my plate with a cup of coffee on the side and a glass of orange juice before nibbling other items available, because it's always tempting to try them.