To take advantage of these prices you will need to prove you are a leisure traveller, on the way to the airport, so you will need to give either your flight numbers or yr holiday booking reference. I don't think you will need to give this when you arrive at the station but you may be asked to give them on yr journey from east-croydon station to the airport.
Going to the airport on the train is great, you can take a nap, read a book (even at night), play a game, or just stare out of the window... The other restriction to buying these cheap train tickets from east-croydon station to the airport is that there must be at least two adults travelling together. But another great benefit is that children go free. All children under five go free, and then one child over five but under 16 per grown up travelling by train to gatwick airport.
be sure to leave enough time to get to gatwick airport early enough to eat, shop and so on, so check the times of trains from east-croydon station before you go. If you have spare time at the airport you can always read or play travel scrabble again! As you have bought yr ticket in advance, you don't need to worry about the opening hours of the station.
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