Is it permissible to combine prayers in France due to the long school day and the prohibition of prayer in public places, bearing in mind that changing specialization later might allow prayer, but with the prohibition of the hijab in the first year?

A Muslim's religion is their capital, and it must be preserved, and everything that would squander it must be avoided. It is advised not to remain in lands of disbelief without necessity. It is better to study one's specialization in Muslim countries. If that is not possible, then choose from the lands of disbelief that which is least corrupt and does not prevent the performance of rituals. If studying is only possible in France, and you are able to perform your rituals and are safe from temptations, then there is no harm. However, you must perform the prayers at their appointed times and choose a school whose study schedule does not conflict with prayer times. There is no excuse for combining prayers throughout the entire study period.