Don't feel bad, majority of people fail on the U-turn, When holding the bike steady and looking over your shoulder it feels unstable and people wobble. Just practice on your current bike. Keep the revs high, hand OFF the front brake, foot over the rear one slow yourself down if you need to and just play with the clutch for your speed. Select gear, foot on brake, life saver, start to pull off, lifesaver, get a good distance into the area, lifesaver and begin manouver. do NOT look at the line, look at the end point, if you focus on the line, target fixation = you're going to ride over it. Also use the space available, my instructor always went on about how most people failed because they tried to do it in such a small area, go right down and you have more time to straighten up at the end! Good luck you'll be fine