I would have thought flying this route either fixed or rotary wing you would be talking to London Information and RAF Valley as soon as possible, not least because of the potential conflict with military traffic. I suspect the aircraft did not reach the coast.
Of course with deteriorating weather and trying to maintain VFR, this aircraft might have been at such a height that no ATS would be available, likewise the aircraft would have dissappered off the radar. Do we have the Valley TAF or Actuals?
In respect of the 'coasting out' call, or using London Information I'm not sure how many pilots actually would do this, even though it is good practice, likewise the wearing immerssion suits.
My guess is that the aircraft did not make the coast.