Terminal 5 is actually on the M25. All of the other terminals are on the M4 which is just off the M25.
The easiest way to get from Doncaster to Heathrow Airport is to join the A1(M) straight down to the M25, and then follow the M25 until you reach the M4 motorway. From there there is a direct route into Heathrow Airport.
There are essentially two main routes: M1, M25 then M4; or M1, across the A43, M40 then M25 again
Take the M40 southbound From Birmingham, then join the M25 and then join the interconnecting road to Heathrow Terminal 5.
95 miles taking this route:Take A1 to the SOUTH from Peterborough to M25 towards HEATHROW (airport).Take M25 to Heathrow.
63 miles taking this route:Take M3 LONDON from Southampton to M25 at JUNCTION 2. Follow signs to M25 HEATHROW airport.Follow M25 to Heathrow Airport. Follow signs to your terminal.
25 miles taking this route:Follow A3 towards LONDON from Guildford to M25. Once you are at M25, follow signs to M25 (W) to HEATHROW.Take M25 around London on the LONDON ORBITAL to HEATHROW. FOLLOW SIGNS to your TERMINAL.
M4, m25, m6
M4, m25, m40, m6
== == Yes, Heathrow is to the west of London, close to the junctions of the M25 and M4 near Staines.
107 miles taking this route:Take A14 NEWMARKET to M11 LONDON via A11 at J36.Take M11 to M25 to WATFORD and HEATHROW AIRPORT at J6.Take M25 around London to Heathrow.
Heathrow Airport is located in the Royal Borough of Hillingdon, which is in west London close to the M25 motorway.
According to AA route planner the best route is via the M25 and A3 this is 24.7 miles the other option is to take the A308 which is 14.8 miles but will take longer in time because of congestion.