Hello Mark Lawley,
thank you for posting on the Microsoft Community Forums.
The NC (New Computer) entitlement typically allows organizations to upgrade to a newer version of Windows, especially in cases where the existing version becomes unsupported or experiences compatibility issues. It sounds like your organization might need to transition to Windows 10 LTSC 2021 because of the recent support changes and compatibility issues with your Dell laptops.
For the most accurate and specific information regarding entitlements such as NC entitlement and support transitions from LTSC 2018 to LTSC 2021, you should contact your Microsoft licensing representative. They will be able to provide detailed information about your entitlements and guide you through the process of obtaining the necessary licenses and installation media for LTSC 2021.
Hope it helps.
Kind regards,
Lei