I'm an ESOL MA student teacher right now. Trust me...you'll make mistakes that goes beyond your imagination unintentionally. Plus, if you don't communicate with your Co-teacher, it can get worse due to miscommunication.
Don't beat yourself around the bush. Get it through and you'll be proud of yourself. Make note of your mistakes so that you don't do them again. Even if you DO make notes of them, sometimes it's difficult to keep it in your mind because so many other things are happening around you. That's why teachers say that their first year is difficult.
I'm afraid of failing too....I thought I'd rock the classroom before student teaching. Things happen and they may not be the way you imagined. Same with your lesson plans. Keep tweeking it and keep communicating with your CT. I am half done with my student teaching, and the more I teach, I'm learning that I need to polish myself more and more.
Good luck!