Apex domains cannot have CNAME records.
Question and response
Question
dig headlandsschool.co.uk. NS
Answer
headlandsschool.co.uk. 5 NS ns10.domaincontrol.com.
headlandsschool.co.uk. 5 NS ns09.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0