To take advantage of the best prices you will need to prove you are a leisure traveller, en route to stansted airport, so you will need to give either yr flight details or your 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 your travels from the station to the airport.
Going to the airport by train is great, you can take a nap, read a book (even at night), play travel scrabble, or just gaze out of the window... The other caveat to buying these inexpensive train tickets from caledonian-road station to the airport is that there must be at least two grown ups travelling together. But another great benefit is that children go free. All children under five go free, and then one kidover 5 but under 16 per grown up travelling on the train to stansted airport.
make sure you leave plenty of time to get to stansted airport early enough to eat, shop and so on, so check the times of trains from caledonian-road station before you go. If you have time to kill at the airport you can always read or play travel scrabble again! As you have bought your ticket in advance, you don't need to fret about the opening hours of the station.
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