Mo
The point about the CRB is that it is there to protect the organisation, not you! You need to take steps to protect both the young people and yourself. I'm a scout leader, and our policy is that there are always at least two adults present at any meeting. If one of the two leaders is late arriving, we would always ask a parent to stay until the other one gets there. If there is only one adult we would not have the meeting! If there is an emergency, you need one adult to deal with that, while the other one looks after the rest of the youngsters. You also need the other adult there to act as a witness in case of any stories coming from confused or frightened children if there is an emergency (you'd be amazed what bits of the anatomy can get bashed when around in a church hall, or tripping over the guy rope of a tent/marquee). In our hall, we typically have 3 or 4 adults for 30 young people (and legally any up to 18 counts as a minor). As soon as we move outside the hall, on a walk or camp etc we have one adult per 6 children and one spare.

The very first training that cub and scout leaders get these day is about child protection. This page here Working safely with young people gives some useful do's and don'ts.

So make sure that there are other trustworthy adults (parents, colleagues, teachers, scout leaders) around when you do this. But don't be put off, and do have a good time with the youngsters...
All the best
KP