Your Eurostar tickets will be sent out to you before you go along with luggage labels.
You'll need your tickets to go through the first turnstile. Then you have to go through luggage control, this bit is a bit of a pain, cos you have to take coats off, plus you have your cases with you and hand luggage, etc., once that's out of the way and you're all dressed again
you head for the departure lounge, there are cafes, shops etc. here and wait for the train to be announced. I think you show your tickets, passports once more before you're allowed down onto the platform. Your tickets will tell you your carriage, seat number and the platform is marked accordingly - it's really simple. There's storage at the end of each carriage for your suitcases.
On board the train Disney staff will come around and hand out your Disney Express service luggage tags and a pack which will include your park tickets, any other vouchers needed for booked character meals, Buffalo Bill tickets etc. In fact the only thing missing is your Hotel Room Key, which you'll get at checkin at the hotel, when you check in is upto you, your luggage will be taken there for you leaving you free to go straight into the park.
At Marne la Vallee, Disney stop you make your way up from the platform and the Disney Express desk is one floor up from ground level.
