Firstly search for "Sonicwall" on the app store. Install the app with a S in a shield icon (As shown below).
Then open the app, click "Connections" and then "New connection"
Enter the following:
Name: Durrington High"
Then click the button in the top right and when asked for a username and password enter your campus provided login.
In the following window that appears click "Allow".
You can then go back to the apps homepage. Click the toggle called "VPN". After the VPN has connected (This can take up to 30 seconds) you will be presented with two options. Click the top one labelled "Remote (Windows 10 Style) - Java.
From the list that then appears click "Microsoft Remote Desktop".
You will then be redirected to the app store. Install the "Microsoft Remote Desktop" application. After you have installed the app open the Sonicwall app again and click "Windows 10 Style - Java" again.
In the following popup window click "Open".
In the window that opens click the toggle called "Don't ask me for connection to this computer again". Then click "Accept" in the top right.
Then in the next window enter your campus provided login again. Make sure to click "Store username and password" so you don't have to enter it every time.
You will now be in the remote session. Click the keyboard icon at the top to use the keyboard. Once you have finished using the remote session go back to the SonicWall app and click the toggle next to VPN to turn it off. Everytime you want to connect you will need to turn this VPN on and turn it off after you have finished using it.