If you prefer fixed pricing to Gatwick, prebook a minicab

https://jasperrxvb617.bearsfanteamshop.com/gatwick-express-timetables-fares-and-when-it-s-worth-it

If you prefer fixed pricing to Gatwick, prebook a minicab. Provide your terminal and flight time, and ask the driver for the best drop-off point to reduce walking.