To take benefit of the best prices you will need to prove you are a leisure traveller, on the way to stansted airport, so you will need to provide either yr flight numbers or yr holiday booking reference. I don't think you will need to provide this when you arrive at the station but you may be asked to give them on your travels from the station to the airport.
Going to the airport on the train is great, you can sleep, read (even at night), play a game, or just stare out of the window... The other caveat to buying these cheap tickets from redbridge station to stansted airport is that there must be at least two adults travelling together. But another great advantage is that children go free. All kids under 5 go free, and then one child over 5 but under sixteen per grown up travelling on the train to stansted airport.
be sure to leave enough time to get to the airport early enough to eat, shop and so on, so check the times of trains from redbridge station before you go. If you end up with time to kill at stansted airport you can always read a book or play a game again! As you have bought yr train ticket in advance, you don't need to worry about the opening hours of the station.
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