UPDATE: Microsoft has clarified how the airports in the various editions of Microsoft Flight Simulator will work, after a request from Eurogamer.
Standard edition players will be able to fly from all the airports in the game, but there are “hand crafted” elements that will improve the experience from those airports included in the different editions. So, the premium edition Heathrow, for example, will be better than the Heathrow in the standard and deluxe editions. But that does mean standard edition users will indeed be able to fly from Heathrow, as well as all UK airports.
Here’s the statement from a Microsoft spokesperson: