As I said previously, London is among the best European cities to visit with children. It is difficult to find a good cultural experience that can be enjoyed by all ages. Everything down to the people in the street makes it a family friendly adventure.
On the second to last day, we spent our morning in Kew Gardens, a beautiful and robust acreage filled with greenhouses and covered in exotic and domestic plants. After which we enjoyed English Tea for lunch, and then spent the afternoon shopping. The next morning, as we had an early afternoon flight, we enjoyed a traditional English breakfast before heading to the airport.
In summary, it is hard to go wrong on a visit to Yon London Town. Think about what interests you, and make time to do those things. If you're a history buff, you've got endless choices. If you're into fashion or shopping, you've got avenues of options. If you're into nature, there are museums, parks, and gardens awaiting your visit. It would take a year of touristing every single day to run out of things to see in London and the surrounding boroughs. The biggest thing is that you have a plan, buy your tickets ahead of time, and eat as many scones as your belly will hold.