Yeah. Stop worrying about it. You're a student. People will know that as soon as you key the mic. They'll cut you some slack. Just think about what you want to say before you transmit and if you miss anything, you'll be asked.
And fly the airplane through the controls - not the radio!
If I could open up Wylie's School of Flying, I'd keep the radio off until a student was getting ready for his first solo Xcountry...and I'd teach initial skills in a Cub at a grass strip...but that's my fantasy and probably not your reality.
Radio's a lot easier than we think it is.
Pitts2112