London Euston to London Luton airport

http://www.thetrainline-europe.com/train/london-euston-to-london-luton-airport-ltn~7001323~7002889

Simpler to walk from Euston to St Pancras then take a train to Luton Parkway for the bus to the airport.

http://www.nationalrail.co.uk/

Where are you coming from to get to Euston station? There may be a direct route avoiding London.
For example, if you are coming from Manchester, Birmingham or similar places on the main line north of Euston, you could get off the train in Milton Keynes and take the hourly bus to Luton Airport. Timetable here: https://bustimes.org.uk/services/bed_1-99-_-y08
From certain places it may also be possible to cut across by train to Leicester or Nottingham, and take a train from there direct to Luton.

If you are booking rail tickets to Luton Airport, note that there is a shuttle bus from Luton Airport Parkway station to the airport itself. Try to book a rail ticket all the way to Luton Airport which includes the bus - if the destination on the ticket says "Luton Airport" the bus is included but if it says "Luton Airport Parkway" you will have to pay an extra bus fare. In my experience, ticket sellers at stations without regular trains to Luton sometimes don't know how to deal with this.

If you do travel to Euston, the walk to Saint Pancras station is about ten minutes.

My sister and I are traveling from Liverpool by train to Euston and we already bought those tickets.

Thank you all for the tips! I think we will walk to St. Pancras and then take to train to Luton airport.
Thanks for the help!

At St Pancras International you will have two different railway companies - which use completely different parts of the station - to get you to Luton Airport Parkway for Luton Airport.

Be aware - there are two similar named stations very near each other, and don't get off at the wrong one. The first of the two is Luton Airport Parkway. That's the one you want. Three minutes further is Luton, which serves the town and you won't have any joy there.

Both companies charge the same fare for that trip, and both have advantages and disadvantages.

Upstairs is East Midlands Trains, who if you look from Euston Road are in the upper left of the station. They run long distance trains on diesel trains with fairly nice carriages and for them Luton Airport Parkway is a first stop on some of their trains. They are fast trains. Those are the advantages.

The disadvantages are that only some of their trains stop there, you come to the train from the dead end buffers so if your train is one of two on the same track you may have a bit of a walk when the train is called, which is often just a couple of minutes before departure, and it can be a bit of a stampede. The other disadvantages is that EMT, if the train is stopping somewhere in Luton, they only stop at either Luton station alternately. They don't stop at both. And you could get on a train to Derby or Sheffield or Nottingham which fly through Luton at over 100 mph and you will miss your flight.

3 floors directly below (2 levels below street level) is the northbound Thameslink platform. These are a bit rough around the edges old electric trains with some 3+2 seating, and also some more modern or even brand new trains. You can't predict what sort of train will turn up. But - they are more frequent, and all except their St Albans terminators stop at both Luton Airport Parkway and Luton. It will probably stop 2 or 3 times before Luton Airport Parkway. They also usually have no announcements of upcoming stations on the older trains.

Bottom line - when you buy your tickets for that segment realise that they can be valid on either company, and when you look at which train is going next make sure you understand which train you are heading for.

Thameslink platforms are alphabetic, A or B, and East Midlands Trains are numeric 1 to 4.

Happy travels