Core comparison
In short: the cheapest way to Gatwick from London is usually the National Express coach from around £10, or a Thameslink or Southern train from about £13.70. The Gatwick Express is the premium option at about £19.90 and is no faster than Southern or Thameslink on the same tracks. For a group of three or more, or a very early flight, a fixed-fare transfer from around £50 can be the cheapest option per head once you split the cost.