I would agree that a leaflet would be a good idea, laying out what is required and what the benefits are. I know that in my area, some people are surprised that you can be part of an 'international' group at a camp within the UK, so that even if you are picked at the selection, there's no guarantee you'll actually go overseas. It could also be helpful to give advice on potential duration, unfamiliar food, costs and fundraising help required/available towards costs. Leaflets could be supplied to the unit Guiders as well as the girls, so the Guiders were clued up on what's involved (because we don't always know anything about it).
'If life were simple - it would be boring!'