We have just heard from the Director of the Prem Center. He said that there were only small minor demonstrations in Bangkok and they posed no danger to tourists or visitors. There were no demonstrations in Chiang Mai or at the Bangkok airport.
It seems like the ruling by the court has been seen as reasonable and has calmed the potential protesters.
Based on his advice, we are going ahead with the school trip. We have contingency plans in case protests break out during the trip. If protests break out during the trip and the students are unable to access the airport, we have already made arrangements for the students to extend their stay at the secure Prem Centre. Teachers will also have work available so that their studies may continue. Obviously, this is a worst case scenario. We do not expect it to happen but we are prepared in case it does.