I recieved a caution for scratchin a car will this show up on a enhanced crb i work with children ?? ?

Yes, it will show up as a caution for criminal damage. Criminal damage is a charge which covers a very wide range of things. It is up to you whether you raise the matter in advance or whether you just leave it to the people concerned to draw their own conclusions. The fact that you have something on your record which is somewhat irrelevant to your type of employment doesn't necessarily exclude you from this kind of work.