Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-08.co.uk. NS
Answer
awsdns-08.co.uk. 5 NS g-ns-328.awsdns-08.co.uk.
awsdns-08.co.uk. 5 NS g-ns-1483.awsdns-08.co.uk.
awsdns-08.co.uk. 5 NS g-ns-904.awsdns-08.co.uk.
awsdns-08.co.uk. 5 NS g-ns-1804.awsdns-08.co.uk.
Authority
The response has no authority records.
Additional
g-ns-328.awsdns-08.co.uk. 5 A 205.251.193.72
g-ns-904.awsdns-08.co.uk. 5 A 205.251.195.136
g-ns-1483.awsdns-08.co.uk. 5 A 205.251.197.203
g-ns-1804.awsdns-08.co.uk. 5 A 205.251.199.12
g-ns-328.awsdns-08.co.uk. 5 AAAA 2600:9000:5301:4800:0:0:0:1
g-ns-904.awsdns-08.co.uk. 5 AAAA 2600:9000:5303:8800:0:0:0:1
g-ns-1483.awsdns-08.co.uk. 5 AAAA 2600:9000:5305:cb00:0:0:0:1
g-ns-1804.awsdns-08.co.uk. 5 AAAA 2600:9000:5307:c00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0