You can use moodle for as your school management system but only till a limit.
Moodle is an online Learning Management system enabling educators to create their own private website filled with dynamic courses that extend learning, any time, anywhere.
In moodle users can register and choose courses. But it's not like a school management system where the website has a database of all students and students can see their grades there.
For your specific requirements, I would suggest you hire a developer and get a custom website with your requirements.