From Heathrow the options are Heathrow Express - Heathrow Connect - Bus to Hayes+Harlington then train - Picadilly line - Coach - Uber - Taxi Only one of thos

From Heathrow the options are Heathrow Express - Heathrow Connect - Bus to Hayes+Harlington then train - Picadilly line - Coach - Uber - Taxi Only one of those options is for mugs, and it's not the Heathrow Express. However from Glasgow you can also fly to Gatwick, or City if you want to avoid thiefrow. However comparing the cost of a non-flexible ticket from Glasgow to London with a flexible train ticket is ingenuous at best.