The school has your data which they see legally allowed to use for the purposes of state education and have created a profile for you on their own instance of Gsuite for Education in order to facilitate your classes. All of this is fine and above board with every current EU law - they have done nothing wrong.

It only becomes a problem when you summise that Google is then scraping said data and using it for nefarious purposes - which is completely contrary to what they state and there is nothing documented to support such an idea.

IMO and others in this thread engaging in a lawyer is just a waste of your time and financial resources. You're already setting yourself up for failure in the fact you're looking for documentation to give your lawyer. If you were serious you would of done your homework (no pun intended) and picked a lawyer who specialises in the field, not some better call Saul character.