Oyster cards at Heathrow?

We bought ours from a machine at the tube station. Very easy.

I don't believe you will find the vending machines elsewhere than at the Tube station.

You can also get them from the visitors/tourists information desks or kiosks

Sharon, are those normal Oysters from the Visitor Centre or Visitor Oysters?

"international terminal" - there are 4 terminals at Heathrow, and all of them handle international flights. They are in different locations, and have different tube and rail stations:

• T1, 2, 3 - in the centre of the airport. Except T1 is currently being rebuilt.
• T4 - on the south side
• T5 - on the west side.

Virgin uses T3, see here: https://www.virginatlantic.com/us/en/travel-information/airport-guides/london-heathrow.html
The tube station is called "Heathrow Terminal 2 and 3". You can see it at the bottom left corner of the tube map here: http://content.tfl.gov.uk/standard-tube-map.pdf
And yes, you can buy an Oyster Card at the tube station.

We normally arrive at T5. When leaving the terminal, just before going down to the tube, there is a desk for (I believe) the Heathrow express. At that same desk you can buy and/or top off Oyster cards. Since it is a real person rather than just a machine, they can answer any questions too. The kiosks in tube stations are easy to use and there is a person around to help out if needed.

Hi Nigel... we just purchased the regular Oysters.. not sure if they sell the visitor ones as well.. sorry

Several times in recent years I have needed to deal with staff and machines in major Tube stations and found very co-operative employees on duty. Some hovered around the machines to lend a hand to clumsy visitors like me. Ticket agents at booths offered suggestions on the most economical purchases. Believe me, four decades ago this would have been an entirely implausible description of London's mass transit. And Oyster cards have made daily travel quicker and easier too.

You can buy a visitor Oyster card ahead of time if there is enough time between your trip and now for it to be delivered. It comes with a pre-selected amount loaded on it but is 5 pounds extra, I got it because I wanted to keep it as a souvenir and will be going back at least once a year.