To take benefit of these prices you will need to prove you are a leisure traveller, on the way to the airport, so you will need to give either your 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 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 travel scrabble, or just stare out of the window... The other caveat to buying these inexpensive tickets from dudley-port station to luton airport is that there must be at least two adults travelling together. But another great advantage is that children go free. All children under 5 go free, and then one child over five but under 16 per grown up travelling by train to luton airport.
be sure to leave enough time to get to luton airport early enough to eat, shop etc, so check the times of trains from the 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 times of the station.
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