Take the Piccadilly line from central London straight to Heathrow; it’s affordable, frequent, and stops at all terminals

https://marcohtjh286.fotosdefrases.com/heathrow-airport-shuttle-and-inter-terminal-transfers-what-s-free-and-when

Take the Piccadilly line from central London straight to Heathrow; it’s affordable, frequent, and stops at all terminals, though it can be crowded during peak travel times.