Yes, schools will change their hours as they did in previous years when Ramadan was during the school year. Legally, they have to because school employees (even non-Muslim ones) are entitled to a shorter working day.
I think all schools change their hours - both my kids' schools have always changed their hours during Ramadan. Last year one of them started at 8.30 am and the other 9 am and they both finished at 2 pm. Mornings were SO much easier during those few days. This year we should get a good couple of weeks of late starts and early finishes as Ramadan starts about the 17 June. Can't wait!