Which airport suits your part of Kent
The location within the county will play a greater role than the airline you are travelling with. Gatwick is the nearest main airport to most of Kent, and journey distance will be relatively short for the western part of the county around Sevenoaks and Tunbridge Wells, moderate for Maidstone and Ashford and long distance one for east Kent coast area. Gatwick transfers from Dover to Gatwick fit into that last category, and it is exactly the type of journey you may want to have booked rather than arranged ad-hoc.
If it is a long haul destination, then the journey will be made through Heathrow airport, accessed from most of the county by M25 motorway and journey length increased without adding to its duration in terms of time, unless it is in the northwest Kent corner. Heathrow transfers from Canterbury rank quite high among that.
When it comes to north Kent and Medway areas, the airports in Essex will become options, and such transfers will cross Dartford Crossing. That fee will be included in the price you are comparing.
The ports of Kent operate in a similar manner to its airports. Passengers embarking in Dover have a set departure time, and a week of luggage; Dover Cruise Terminal to Heathrow transfers take care of the connection by plane. The Channel Tunnel at Folkestone and ferry services in Dover use the same booking procedure.
Choosing your vehicle
If the trips are long, and it pays off to provide comfortable transport: Business class for all except a fourth passenger in Standard, Business XL, the largest MPV of the line-up, when travelling in a family party with a fortnight of luggage. First class and Executive class fit the trips where driving should be effortless.
Cruise and group bookings involve more than one car. Make sure you book them all to maintain the schedule.
Group transfers from Kent, including cruise parties departing from Dover, are offered using several cars, not a minibus.