Q: Is it possible to board and pay for a bus tour from Waterloo Station to visit some sites in London during a one day layover? We will be arriving via the Eurostar at 09:30 am and flying out the following morning, and we would like to check our luggage at Waterloo, then visit a few sights before making our way to the Comfort Hotel at Heathrow.

A: I’m not sure you can pick up a bus tour from Waterloo station but you are ideally placed for easily seeing lots of London sites.
From Waterloo station, it is a short walk to the river, where you can walk east along to Tower Bridge. That would take you past places such as the London Eye, the south bank centre (entertainment area), the Globe theatre, Tate Modern, borough market, HMS Belfast and Tower Bridge. (Have a look at my cultural walk).

Or from Waterloo, once you hit the river you can walk west, then across Westminster bridge to see Big Ben, Westminster Abbey and through St James Park to Buckingham Palace. Also Trafalgar Square and number 10. (Have a look at my royal and political walk).

Then you could make your way back to Waterloo station and take the underground to Paddington station, where you can catch the Heathrow Express to the airport.