Apex domains cannot have CNAME records.
Question and response
Question
dig t-mac.co.uk. NS
Answer
t-mac.co.uk. 5 NS ns-1754.awsdns-27.co.uk.
t-mac.co.uk. 5 NS ns-352.awsdns-44.com.
t-mac.co.uk. 5 NS ns-883.awsdns-46.net.
t-mac.co.uk. 5 NS ns-1106.awsdns-10.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0