Since you've already missed the annual Rally School, perhaps the next best thing for you to do is to show up (with a car, a navigator and pen/paper) and compete in a beginner-friendly navigational rally. The next such rally is the June Mini Rally on June 14.
Provided you arrive early, there will be plenty of people around at the start to give you enough information to finish the rally. You can use your own car (no special car preparation is required) and entry fee is only $25.
Look for Mini Rally Series on the MLRC web site for more info. Good Luck!