As Monty has replied this topic has been aired so many times over the 10 years I Have been travelling with JY, and the amount of tours has increased over the years for travelling in the school holidays, the tours would go up so much in price as its the most expensive time of the year to travel, and there has to be a certain group size to make it viable, and the demand isn't there...I am very happy to stay at home in August as its our summer and I think many JY travellers feel the same..I know this doesn't help your situation, perhaps there is a travel group that specialises in teachers etc...
Cindy