To take advantage of these prices you will need to prove you are a leisure traveller, en route to the airport, so you will need to give either yr flight details or your holiday booking reference. I don't think you will need to provide this when you arrive at redbridge station but you may be asked to give them on your journey from the station to stansted airport.
Going to the airport by 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 train tickets from the station to the airport is that there must be at least two adults travelling together. But another great advantage is that children go free. All children under five go free, and then one kidover five but under 16 per grown up travelling by train to the airport.
be sure to leave enough time to get to stansted 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 travel scrabble again! As you have bought your train ticket in advance, you don't need to fret about the opening times of redbridge station.
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