To take advantage of the best prices you will need to prove you are not a business traveller, en route to the airport, so you will need to provide either your 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 your travels from the station to the airport.
Going to luton airport by 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 caveat to buying these cheap tickets from the station to luton airport is that there must be at least two adults travelling together. But another great benefit is that children go free. All children under 5 go free, and then one child over five but under sixteen per adult travelling by train to the airport.
make sure you 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 have time to kill at the airport you can always read a book or play travel scrabble again! As you have bought yr train ticket in advance, you don't need to fret about the opening hours of the station.
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