Hello. I will be traveling with my 10 year old daughter from the US to Seville next week. We have a 6 hour layover in Heathrow. We land at 6:20am and our departing flight is 12:20pm. We are arriving on a United flight. What is the best way to take her out of the airport and to see a few things in Central London? I was thinking the Heathrow Connect train but then.... ? I was hoping a hop on / hop off bus but concerned about the time. Suggestions? She is only 10 and doesn't need to see alot but I thought it might be fun to see a few key sites. Thank you!