From the West End, take the Piccadilly line; estimate around 50 minutes to Terminal 5

https://www.scribd.com/document/1074929924/National-Rail-to-Heathrow-Routes-Transfers-and-Tickets-Explained-232993

From the West End, take the Piccadilly line; estimate around 50 minutes to Terminal 5, and consider traveling off-peak for a more comfortable journey.