To/From London area airports 

The content provided below is only for rail transport into Central London. Yes you can hire a car or take a taxi. These options will be very costly for one passenger, but can offer potential cost savings if you have a large group. Note: With all of the information below, it is best to leave extra time… that is, cutting it close may make you miss your flight.  In my experience, if a train states 30 mins travel time, I allow 50-55 minutes to make sure I do not have to rush. 

Heathrow Airport

From Heathrow, there are 2 main rail options into central London. The first is an express service called the Heathrow Express. The other option is to take the Underground Picadilly line into central London and transfer from there.

• Heathrow Express — The Heathrow Express (HEX) is a very quick, express train to Paddington Station. The trip takes 15 minutes from Terminals 1,2,3 and ~20 minutes from Terminal 4 and trains arrive every 15 minutes. An Express Class ticket (2nd class) is £14.50.
• Allen's take — I would not spend the extra for First Class – the trains are mostly empty, the trip is 20 minutes and even the 2nd class is clean and very nice. Save the money for some Fish 'n Chips!
• Allen's take — This is a great option for an individual or couple. Once you have more than 3 people in your party, the cost outweighs other options (car hire)
• Heathrow Connect — The Heathrow Connect (HC) operates on the same line as the HEX but is a stopping train. There are 6 stops en route to Paddington Station. The trip will take approximately 26 minutes. A single fare from Paddington to Heathrow is £9.50. This is not as popular as the HEX or the Underground but offers another option for passengers wanting to save a few dollars. If you need to go to Terminal 4, you will need to switch to a HEX train at Heathrow.
• Underground — text

Gatwick Airport 

From Gatwick airport, the easiest way to Central London is to take the Gatwick Express (GEX). Trains run every 15 minutes and take 30 minutes to reach Victoria Station. From Victoria you can either board the Underground (tube) or catch a cab to your hotel or destination. A 2nd class (called express class) ticket is £14 single/£25 return.

London City Airport

rail

Stansted Airport

From Stansted airport, the easiest way to Central London is to take the Gatwick Express (GEX). Trains run every 15 minutes and take 45 minutes to reach Liverpool Street. A 2nd class (called express class) ticket is £15 single/£25 return. Liverpool Street provides connections with the national rail network and with four of the most important London Underground lines – the Central, Circle, Metropolitan and Hammersmith & City lines.

Luton Airport

Thameslink rail service is the quickest way to central London from Luton Airport. You need to get off at Luton Airport Parkway. There is another Luton station but that is not the correct one. Also note, you will need to take a bus from the rail station which you will need to allow time for this bus trip.  The rail trip should run under 1 hour.