Just be thankful that your children will have the opportunity to learn that there are lots of different sorts of people in the world and lots of different ways of living. Education is more than the three Rs you know!
A school not far from us had taken in travellers' children from an illegal site. They only wanted to learn how to read and write and add up (the three Rs you know) and were not interested in anything else, such as topic work, drama, games, art, etc. They would turn up occasionally and leave when they had had enough.
However, a proposed site which is legal may have a different impact and you may find the diversity refreshing rather than disrupting!