You can manually apply the details directly to the invoices. Check out this article on how to personalize your invoices. You can decide what info your customers see or add the info that matters most to your business.: Customise invoices, estimates, and sales receipts in QuickBooks Online.
Another option would be to look for a third-party application that can help raise invoices with LUT. Just go to the Apps menu and type in some keywords.
To learn more about the zero-rated supplies and Letter of Undertaking, you can check out these links: