The "f#ck it" approach is a terrible idea but there comes a point when you absolutely know you can do something and no more preparation will help, you just have to take a deep breath, visualize the movement a few times, let go of the fear and do it. If you are comfortable with them in the gym (not "I can do them", but comfortable), head outside onto the grass, find a spot with a slight downhill grade, pretend you're in the gym and simply execute the move. Front flips are low risk, pretty much the worst that can happen is you will land on your back or ass. Good luck!