I will be flying out of Terminal 3 in a couple of weeks. First transatlantic flight and as a nervous flyer this is a bit of a big deal to me. The flight is in the late afternoon so would like to 'make a day of it' at the airport to relax me, i.e. a nice lunch, bit of shopping and a couple of drinks. Am I best staying landside or going airside? Dont want to go airside too early only to find a tiny duty free store and a Costa!