It is very easy to travel to the Dam.

Either use a flight booked a decent amount of time in advance (earlier booking=cheaper flights), or you can also go by coach but that is a massively long journey.

I once motorbiked it to Rotterdam...left early mornign and got there by about 9pm, but only coz the weather was a bit shit and I had to stop for warm drinks more often than I would've liked.

If you get a car, you can cross the water at Harwick straight to Hook of Holland and drive up to the Dam, but be warned, the Dam is NOT a place that is welcoming to cars that much.

I think there is also a train option but not sure if it goes past Brussells.