Waterloo wrote:You'll have to use it at St Pancras station (exactly like a ticket for a subway...).
Explain??
Ou have to print your ticket on a paper sheet.
On this paper sheet will be printed your name, the destination, the hour of departure and... an "olographic" drawing.
You will have to put this "olographic" drawing on a electronic screen at the station (Eurostar section) and the gate will open.
You'll have only, then, to pass the custom office.
It's the same thing at the Lille Europe station... (I'm living near Lille)
And I think it'll be the same at the Bruxelles station when you'll go back...
You would have to print you return tickets also : it's better to have them before your departure...
Very easy to use : my children did it this summer.
Hope you'll have a very good trip.
Waterloo is really a very nice site.
Don't forget to take a big bag for all the books and figures you'll purchase.