Apex domains cannot have CNAME records.
Question and response
Question
dig psychonet.co.uk. NS
Answer
psychonet.co.uk. 5 NS ns2.psychonet.co.uk.
psychonet.co.uk. 5 NS ns3.psychonet.co.uk.
Authority
The response has no authority records.
Additional
ns2.psychonet.co.uk. 5 A 77.104.162.218
ns3.psychonet.co.uk. 5 A 65.21.91.95
ns2.psychonet.co.uk. 5 AAAA 2a02:8010:d015:0:0:0:0:123
ns3.psychonet.co.uk. 5 AAAA 2a01:4f9:3b:4384:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0