know its not the same long journey but i have been to mid wales and london with rhiannon for her to meet family, the first journey (mid-wales) was a disaster, i was so uptight about it that she picked up on it and played up, winging, fussy etc.. and the more she did it the more uptight i got, hence vicious circle...
the second journey (to london) was better, i said to myself, go with the flow, when she fussed i just smiled and tried to get her to laugh and it worked (well the journey was better than the first..)
guess im trying to say go with the flow, OH will be there lean on him when you feel its geting to much eg maybe in the airport lounge ask OH to wheel him about while you grab a coffee or cold drink?
dont be surprised though, as young as brennan is he might not fall asleep when he is due a nap as everything will be so new he might stay up and nosey XXX