If this happens to other board users, try to stay calm and relaxed as he'll be just as nervous as you. Maintain eye contact at all times and allow him to speak first. Never ask for selfies or signed photos as this will only pressurize him into beating a retreat. By now he will be well versed with the unfolding scenario, so if I could offer any advice then just be yourself.
I have met many famous people throughout my travels and to name drop a few would be a pleasure such as Prince Charles who I grafted with, Fred Dibnah, Jimmy cricket, David May, Bellamy, Don Estelle and his afghan hound, Ian Botham, John Stapleton a few times, Noel out of the oasis, the city ex footballer who looks like him out of top gear, Billy Beomont, Nathan Moor out of Brother Beyond who and a good pal of mine and even Sir Bobby Robson. Sir Bobby chatted to us for at least half an hour at Ireland international but only at his own behest. He was a proper gentleman being both funny and anecdotal.
So if any of you are lucky enough like Mr Eccles to actually have the pleasure of meeting up with the leader, then don't overpower and allow him time to breath. Remember they are only a man like you and I and all glory is fleeting.
I have met other important dignitaries from the Moon such as Mr Flower, Mr Danamy who I have to say was an excellent bass baritone, Bob De Niro, El Prersidente, Mr Blue and a few others that wouldn't appreciate a mention as they are grey men.