I have a 9:00 a.m. flight to Munich on July 25th. If I already have my boarding pass prior to getting to the airport should 2 hours be long enough to get through Security? I am a US citizen.
Should be plenty of time. There is no emigration check, only the normal bags / person screening.
Under normal circumstances, I would say yes - two hours is plenty. However, remember that the Olympics start on 27 July. While I would expect more issues coming INTO Heathrow for the Games, you wouldnt be wrong to add a little extra time just to be safe. Again, though, I would expect the delays to be entering the UK via Heathrow, not departing. If Nigel or one of the regular UK posters is reading, perhaps they can lend some insight as to what is being recommended in-country.
Thanks, Tom, sorry - no knowledge - don't fly