Cruisemum, I regret now telling you of my experiences. I meant to show that you can have a terrifying experience or panic attack and get through it, and cope with it. But now I worry that maybe this thread is not so helpful to you. Maybe it's making you dwell on the worrying aspects, and winding you up about your forthcoming trip, rather than helping you to chill and gain confidence.
Perhaps you ought to approach this, prepare for it, like you might prepare for labour. With breathing and calmness, with visualisation of how you would like to move through it and of a happy outcome. With the knowledge that, at the end, you will be flying on endorphins and very pleased with yourself. With making sure that everything is ready so that you don't have a mad panic to pack everything in a final rush.
Does that make sense?