From Heathrow Terminals 1-3 train to Paddington Rail Station, bus to London Euston, then train to Northampton. 1hrs 46min £49. From Heathrow Central Bus Station line 230 bus to Brook Furlong, Milton Keynes Coachway (Milton Keynes Coachway Car Park), bus to Central Milton Keynes, Food Centre (Central Milton Keynes Food Centre B4), then bus to North Gate Bus Station. 2hrs 10min £12. From Heathrow Central Bus Station line 140 bus to Harrow & Wealdstone then train to Northampton. 2hrs 37min £21. From London Heathrow Airport (LHR) drive to Northampton. 1hrs 10min £14.