The ability to create an invoice with an online payment option in the QuickBooks International version is unavailable, James.
I can see that this feature will be beneficial to your business. Although the option isn't available, you can consider exploring a third-party application that integrates with QuickBooks Online (QBO) and allows your customers to make online payments.
To find apps compatible with QBO, visit the QuickBooks App Store or use the Apps menu within your account.
Here's how:
Navigate the Apps tab.
Click Finds Apps.
In the Search for an app field, look for an invoicing app.