Your School email account can be accessed via Microsoft Outlook on any School PC.
Google Mail is not available for students on their school email address.
Email can be accessed from any browser on any device by navigating to https://outlook.office365.com and signing in with your email address and school password.
If you are using your iPad, you may just need to re-enter your password.
Open 'Settings' > 'Mail' > 'Accounts' > 'Office 365 - School Email' > 'Account' and enter the password that is used to log on to the network.