Train to and From London?

For Rotterdam consider flying from London City Airport - can be less than £40 one way for the flight. Even adding on the journey into Rotterdam itself the cost would be hard to beat by rail, which is around £63 (change at Brussels or Lille according to schedule).

this is a duplicate question.

my question is on the other thread in the Netherlands section of the Helpline.

Rotterdam will be about the same price.

You could fly, but the same questions about when and how many and what apply.