In reply to Bingers: I was head of Educational Visits in a state secondary till three years ago (so what I say could be out of date, but I don't think it is). Certainly when I left, there was no requirement to obtain a CRB disclosure for UK host families for exchanges, and no way to CRB the foreign hosts.
In one way, it did always seem a bit odd - if someone regularly came into the school to teach or coach pupils, under supervision, they needed a disclosure, but we sent our pupils to stay in the home of another family, abroad, with no investigation into whether they might be axe murderers.
Of course, the right way to think about it is to compare the risk and benefits on both sides. To my knowledge there's never been a major incident that a CRB disclosure would have prevented on a foreign exchange, so it would seem the odds of it happening are probably low, and the benefits to the millions of kids who do it obviously significant.
MFL teachers around the country dread Gove or some other moron spotting this anomaly and insisting on them - because that will be the end of exchange visits as we know them. So I'm saddened and slightly worried that the FA is now asking for them. And to charge for them is just bloody cynical.