Driving to Heathrow? Follow the M4 or M25 depending on your route

https://www.scribd.com/document/1074920514/Getting-to-Heathrow-from-Gatwick-Easiest-Inter-Airport-Transfers-178501

Driving to Heathrow? Follow the M4 or M25 depending on your route, then follow airport signs; pre-book parking or use a meet-and-greet service to save time.