You can easily create school emails for your students. We recommend using Google Apps for Education. With this tool, you can create email addresses for your students at your school's domain. Please go to https://www.google.com/edu/products/productivity-tools/ to check out the possibilities.
If you don't want to create school email addresses for your students, you can use fake email addresses as usernames for Holmwood's. We recommend using fake addresses in the form firstname.lastname@example.org.
NB. Using fake email addresses will not affect the use of the course. However, students will not receive email notifications or be able to reset their own passwords if they forget it.