The magic formula is
=B2&"@mtbhs.sa.edu.au"
(B2 in this instance means the cell where the first student ID is ...could be a different cell)
Doctopus is clunky, but the instructions will help you create a file for each student in your class so you can watch student work evolving. First generate a g suite account class list. Great for drafting, keeping track of student work and evidence of progress through a task.
You can make a tab with every students name with a few clicks. https://alicekeeler.com/2014/12/30/google-sheets-assign-each-student-in-the-roster-to-a-tab/
<iframe src="https://drive.google.com/embeddedfolderview?id=FOLDER-ID#grid" style="width:100%; height:600px; border:0;"></iframe>
<iframe src="https://drive.google.com/embeddedfolderview?id=FOLDER-ID#list" style="width:100%; height:600px; border:0;"></iframe>