To take advantage of these prices you will need to prove you are not a business traveller, on the way to the airport, so you will need to give either yr flight numbers or your holiday booking reference. I don't think you will need to provide this when you arrive at wood-green station but you may be asked to provide them on yr travels from wood-green station to luton airport.
Going to luton 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 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 luton 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 wood-green station before you go. If you end up with spare time at the 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 worry about the opening hours of the station.
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