If you have PRN medication that might help. If you think some diazepam would be helpful make a GP appointment and explain you're fear of flying and I am sure they will prescribe a few in case you want them.
Don't drink, alcohol can make you feel worse on its own and will dehydrate you which you don't need.
Remember its one of the safest modes of transport. Billions of people travel on planes each year, many thousands every day.
I would check out 7 11 breathing techniques and practice them each day till you feel you can control your panic [This site explains it well...
http://www.wiltshirehumangivens.org/...breathing.html]
Hope something of that helped x