Bobby - there is some info on the internet about the brethren - you probably need to search under plymouth brethren - they are the wider church from which the "closed and exclusive brethren" are a split. I found this:
"What should I do with the "PB" children I teach?
"Several times a year, I get an email from a teacher who has several children in his/her class who are from a "Plymouth Brethren" background. These children are not permitted to eat with other children, use computers, read some of the standard books in the curriculum, etc. The teachers are asking me for information about their religion and advice for what to do with the children.
"First of all, let me say that this is not descriptive of most "Plymouth Brethren" families, open, closed or exclusive. I suspect that the families involved are part of some "exclusive brethren" group, but I have no way of knowing which one. My advice is that you respect the religious beliefs of these families, and treat them as you would any group that believes in extreme separatism from the world (such as the Amish or the Old Order Mennonites). Any attempt to push them to be more "outward looking" is likely to meet with suspicion and resistance. If you seek to work with these families to find alternative curriculum and activities for the children, you will reduce the suspicion, and increase the chances that these children will be able to stay in school beyond the minimum required by law. "
Apparently they have a bible school in Aukland but seem to be bigger in Australia
Hope you job works out ok for you. Do let me know!