London Luton Airport
Luton Airport barely existed before it was chosen as a base of operations by Easyjet, and it is still almost exclusively served by budget airlines. The sheer number of destinations which Easyjet fly to from here make it a good place to connect between flights. It is also slightly more convenient for central London than Stansted. If you have the choice between here and Gatwick however, Gatwick is probably the better option. The terminal itself is pretty busy, with plenty of cafes and shops.
Getting there on foot
Luton Airport is nowhere near London. You can quite easily walk there from Luton itself however, which is only about 8km away. Just follow the signs.
Getting there by public transport
Train.
There is not a station at Luton Airport itself. A regular free bus operates however to Luton Airport Parkway station (15 minutes, every 15 minutes). From here Thameslink run trains to central London (40 minutes, every 15 minutes). Many of these continue to Gatwick and Brighton. Prices are pretty reasonable at 11 pounds, although the trains are pretty unpleasant.Virgin Trains also run a coach from Luton Airport to Milton Keynes Station. This allows easier connection to stations in midlands and northwest of England via the West Coast Mainline. Integrated tickets are available to stations on the National Rail network. Buy tickets before you board from the ticket counter in the airport (or from the usual National Rail ticket outlets).