From Croydon, hop on Southern or Thameslink from East Croydon station

https://riverrwip399.theglensecret.com/gatwick-airport-shuttle-services-hotel-and-terminal-connections-1

From Croydon, hop on Southern or Thameslink from East Croydon station. Trains to Gatwick are frequent and fast, often taking less than 20 minutes platform to platform.