If you prefer fixed pricing to Gatwick, prebook a minicab

https://hectorctuk095.wpsuo.com/gatwick-express-vs-thameslink-vs-southern-which-train-to-gatwick-is-best

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.