As Pete says, your instructor will stay behind and make sure you are as safe as possible. As it's training, they'll make sure you're up to a competent level on the bike/scooter before taking you out onto public roads. Trust that your instructor will not put you at any undue risk. As for gaining confidence out on the road, if you have a bicycle, take that out for as many rides as possible and think about your positioning on the road. I found that when riding the bike, the positioning wasn't much different ie being in the middle of the road when turning right, checking over your shoulder before making any turns to make sure nothing is coming from behind. Most of all when it comes round to doing the CBT relax and enjoy it. If you've not ridden a powered 2 wheeler you'll love it!