Emma, when I flew to London a few years back, I was advised 2 1/2 hours ahead of my flight departure time. With all the extra security checks they are doing now, you might want to add another 1/2 hour (or even more) onto that. Personally, I try to arrive so that I am through everything and sitting at my gate an hour ahead. That way I know I have time for the loo and to try to relax. I LOVE traveling, although it makes me a nervous wreck cuz I'm always afraid I will get lost or something will go wrong). So I've learned to plan time for my anxieties!!! So far, I've been lucky! Have a great flight and see you soon!!