Kent is a big county with no major airport inside it, so every flight starts with a cross-county run. Gatwick is the usual answer for the west and centre; Heathrow and even Stansted come into play from the north-west. Here is the logic.
Gatwick is the default — but the train fights you
For most of Kent, Gatwick is nearest. The catch is rail: there is no direct line, so the train means going into London and back out, often with two changes. That is slow and miserable with luggage. By road it is one clean run on the M20/M26/M25. See Sevenoaks (35 min), Tunbridge Wells and Maidstone to Gatwick.
When another airport makes sense
- North-west Kent (Dartford, Gravesend) can reach Heathrow on the M25 without much penalty if the fare is right.
- Stansted via the Dartford Crossing and M25 is viable for the right flight from north Kent.
The disruption angle
Because the Kent–Gatwick rail route already relies on London, it is fragile. When the Gatwick Express or Thameslink go down it cascades — see Gatwick Express cancelled and Thameslink to Gatwick suspended. A pre-booked car sidesteps all of it.
Cruise from Kent? Dover is on the doorstep — see the Kent taxi hub for ports and the fly-cruise runs.