Speak to the chap who decides who goes on the course.
Not sure where your at in terms of information, or who you've spoken too, or how your board works, etc, etc.
In Northamptonshire, you would basically need to speak to the "cricket board manager" or whatever they might be called. Here this chap is they guy that runs/overseas all the age group sides, and all the local clubs.
It used to be that there was a limit on the number of people they could put forward each year, and it was not very many either, like 2 or 3. Figure that one of those places will likely be for some one from the county (I. E a player etc) and that why it's so hard to get a place.
Try and get into see the bloke is all I can say, but your going to need a good body of evidence to justify your claim to a place.
It might seriously help your case if you get involved with girls cricket. The boards have some ridiculous targets to try and reach, and so they tend to look very positively on such things.
I don't know why it's so hard to get on the course, it's (No Swearing Please) (No Swearing Please).