So...in the event of no further clearance from atc, are we expected to continue flight plan route?
If due to comm failure it is suggested by ICAO unless VMC to an altn apt.
The UK to Iceland portion actually enters oceanic airspace, and this we did without a clearance from Scottish (?)
Shanwick is the only NAT OCA where it's mandatory to hold before entering when without clearance.
Unless, again, it's due to comm fail.
In this case, according to MNPS Manual, depending if received a clearence or not you may continue according to the last clearence or to your FPL.