This is dependent on the delivery method you choose when checking out.
When Home Print is selected at checkout, your tickets will be sent via a link in your confirmation email. The confirmation email subject line will read "Ticketing Site | Order Confirmation." Open the email and scroll down to where it says "Click here to print your tickets".
If you selected Print Now as the delivery at checkout, your tickets will have opened in a new tab in your browser when your order was completed.