Anyone wanting a good start into the competitive racing world, could do a lot worse than dabbling in Cyclocross.
The new season is upon us, and there is a local series that is very accessible with classes going down to the U8s. There is pretty much a race each week - normally on Sundays but with the occasional Saturday. You don't need a dedicated Cyclocross bike - a MTB is perfectly adequate.
The following link will take you to more information.
Also check out videos on YouTube if you want to see what it is all about