Hello, We will be in London in July and then going onto Amsterdam. Is it best to take the train or fly?
The Man in Seat 61 covers some of the options -- http://www.seat61.com/Netherlands.htm
Eurostar would be be about 4 hours 38 minutes from London St Pancras.
I am also traveling from London to Amsterdam and settled on the Dutchflyer sail-rail from Stena Line
Flying from London City Airport is said to be fastest.