In short, you do not need permission from your school. The review you are writing is your personal feedback regarding your experience when using a product or service.
SchoolAdvisor has made it clear in our terms and conditions that any review written is in no way representative of the school’s views - it represents the view of the individual writing it. You, therefore, don’t need permission from the school. As long as you have experience using the product or service, you are eligible to review it.
So, now that you know you have permission...
I hope that you found this article helpful. Here's a couple others you might want to have a look at.