Surely SUDO is OK?

Can I not just use SUDO when I need administrative elevation on a MAC or Linux?

Unfortunately the answer is NO!

The standard requires that you DO NOT use your day-to-day account for administrative activities and therefore you need to have an account for day-to-day (your business app, email and internet access) and then another account for any admin priviledges.

Basically a SUDO -U or SU to a different user account is compliant with the standard, just SUDO on your existing account is not compliant with Cyber Essentials.

See Account Separation