HotshotJacko, the odds are not decent at all. When I did my stage 2, only 1/3 made it to the end of the day. I haven't done stage 3 yet, but based on the infographic on the NATs website I imagine an even smaller fraction will make it through that.
That said, if it's something you want to do you might regret not at least trying. You could always wait a few years until you are no longer a student and have a job, that way the money won't be as big of an issue.