Drum
I learnt to fly 10 years ago, and was absolutely hopeless on the radio. Some may still think I am, but back then my very patient instructor suggested I write myself a little crib sheet, with spaces for the variables - a/c reg, ATIS code, runway in use etc, etc. It worked and after a bit I didn't use it. I still find the radio intimidating if I have not been flying for some time, but just think carefully through what I have to say, run it thru' in my head a couple of times, then happily muck it up on the radio and reckon that no one is perfect!
Don't give up, its definintely worth all the effort in the long run. Good Luck