Hi,
I can be an anxious flyer at the best of times but I don't let it stop me from taking holidays. Things I do to help the situation is request an aisle seat, I hate to feel squashed between people. This way I can get up and stretch without bothering anyone next to me. If you can get a bulk head seat or one in the emergency exit aisle even better for leg room.
Take a gravol or dramamine 30 minutes before take of. This helps with nausea and nerves and will make you drowsy. Take a good book with you, it takes your mind of things and makes the flight go quicker. If the flight offers a movie, watch it. I would not recommend alcohol, will just upset your stomach more and the altitude makes you feel light headed. Try and keep cool, don't wear heavy clothing and use the air vent above your seat.
Just think about what you have to look forward to when you arrive at your destination and you'll be fine.
curlyq