Interesting Preponderances, this day, the Super Bowl

My question for the children of Hailsham is this:
If you know that you're going to be an organ donor who will live a stunted life of hospital visits and recovery, why not escape to another country?
This may sound much like the questions posed by classmates except that I'm wondering whether this thought crossed the minds of the students after leaving Hailsham, once they are on their own and can fend for themselves in some sense. Another question which bothered me was where the money was coming from to support the students while they were in the Cottages, as they did not seem to have any real responsibility other than keeping themselves alive and well read.
I understand the question of why they would not escape to another country would probably seem a ridiculous idea to most Hailsham students because they've always been resigned to their own fate, but it seemed to me once they were allowed a little more freedom and the opportunity to travel around England, they would also want to travel abroad, and perhaps stay there.
The question of where the money came from is dealt with somewhat near the end of the story while Kathy and Tommy discuss "Deferrals" with Miss Emily but I began to wonder whether or not they would receive enough funding to basically raise however many children were at the school to adulthood. This brought up another question for me, is it truly pheasable to raise a human being all the way to adulthood just to harvest the few organs you can while they're donating? It would almost seem easier to just develop a way to grow individual organs, rather than entire human beings.
I have to say that upon finishing this book I was quite satisfied with the ending, and the loose ties that came together to form a solid story with plenty of interesting commentaries on life as we know it, and the possibility of life in the future.