I studied at a preparatory school where all of the students took it for granted to go to university or college.
I went to preparatory school and didn't have any question whether or not I should go to university or college.
「進学校に通っていたので、大学行くことに疑問を持たなかった」
進学校 a preparatory school, a prep school
当然のことと考える、思う take for granted
少し違った角度の表現となりましたが、
I studied at a preparatory school where all of the students took it for granted to go to university or college.
学校は進学校で、そこではだれもが大学に行くことを当然と考えていました。
もう一つは素直に表現した例です。
I went to preparatory school and didn't have any question whether or not I should go to university or college.