Someone who is used to foreign travel, I am hosting an exchange and need to get my exchange partner back to Heathrow (Terminal 5) for their flight at 2pm. I know that check- in needs to be 3 hours before. I haven't done long-haul for ages so need some help, being a bit thick I think. Does that mean the desk will open 3 hours before or that they need to have checked in completely 3 hours before? All advice gratefully received as I don't want her to miss her flight or be hanging around for ages either.