i felt exactly the way you do when i was deciding wether to fly or not. and i still get very nervous before every lesson. but once im up there, it is totaly worth it to me.
im hoping that the fear thing will pass as i gain experience, but if it doesnt, what the hell. i will only be a better more aware pilot for it right.
fears not always a bad thing. you should also remember that if the aircraft is well maintained, and the school is professional chances of error are extremely low. also should an engine fail if the 1 in a million does happen. you will not fall out the sky like a brick. single engine aircraft make excellent gliders!