UK AIC 52/2004 requires flights with a comms failure and no oceanic clearance to remain clear of oceanic airspace.
However, the UK AIP ENR 2-2-4-14 para 17.3 simply "strongly recomends" that flights experiencing R/T failure prior to NAT entry remain clear.
That same section of the UK AIP gives advice on what to do if the pilot decides to ignore the recomended procedure and press on.
Regards,
DFC