You may like to have a look at
http://freespace.virgin.net/neville.mizen3/
These quizzes appear twice a year. They are excellent, can be supplied by post or downloaded from the internet. No need to pay money up front. We send money with our entries, AND the charities can benefit from Gift Aid. I have sent money off before for quizzes that have been ten minute wonders. Much as I wish your project success, I'm not going to pay �2 for a quiz of unknown merit.
There are numerous people on Answerbank who involve themselves with the Rainbow quizzes, and I hope one or two of them will come along with some comments.