If you are looking for any beautiful and peaceful place to chill in London or to eat an ice cream, I suggest you South Kensington. It's such a beautiful place, with an amazing architecture. It's also known as a home for French expatriates. You can find there the French consulate, the Lycee Charles de Gaulle and the French Institute, home for a French cinema.
In order to take a break, we went to Scoop, a cute place where you can find happiness by eating ice creams, cakes and even churros ! I like the ambiance of the place.
If one day you ever get a chance to go to South Kensington, take a break and go there. It's near the underground station, I promise, you won't be disappointed!