As already said yes there are kids races on. They tend to start on a handicap basis with different ages going off at different times as some of the older ones are pretty big and strong riders right down to kids who can barely get their leg over the top tube. All races are separate, just run simultaneously.
Re the ladies there has been a separate ladies race run whilst the 3/4 and E/1/2 races are on. You just need to keep an eye/ear out for calls etc from riders in other races passing you (I'm assuming you won't be able to keep up with the E/1/2s but would be delighted to be proved wrong
). The ladies race tends to have a fairly small field and get scattered about and spread out all over the circuit as the standard varies greatly from the pretty new to racing up to Charlotte Blackman. You'll still get a good race though and there are a lot of people on a small circuit so you won't be miles from any other riders at any point.
Getting there early with the nipper will give you a good chance to ride a few laps of the circuit yourself to suss it out a bit. Best bet would be to do a couple of hard effort laps as well as general recce to give yourself an idea of what the corners/hill are like (and feel like) at speed.
Good luck.