Can't think of anything that would have 10 seats other than a minibus as even Zafira's only have 7. For the latter, your probably best talking to a van retailer as they often sell minibuses as well. Volkswagon seem to be a popular make with schools.
A slightly cheaper option might be to look for van to minibus conversions, although be very careful to chose a good company as they need to be done to very high standards.