Which railway station is more convenient to change trains from London Heathrow Airport?

There are several big railway stations in London, except Paddington mentioned by Nana's friend, St Pancras, King's Cross Station and so on.

Paddington generally goes west and south; St. Pancras is the international station, the starting point of Eurostar to the European continent, and the other big station, King's Cross Station, is the starting point of the northbound train.

If you want to go to Sheffield from Heathrow Airport, you should take the Tiepikadili Line directly from Heathrow Airport to King's Cross Station, and then transfer there to Sheffield.

Of course, if you have to go to Paddington, you should take the Heathrow Airport Express from the airport and go directly to Paddington, the terminal.

Heathrow Airport is the airport express, except for the subway line.

I hope the above information can help you.