RN Firefly intruder missions?

Did the Royal Navy ever use the Mk1 Fairey Firefly as an intruder aircraft over
France/Holland/Norway during 1944 1945? Its long range and heavy firepower
would have been an asset.

Not that I am aware of - but then if they had the RAF would probably protested!
Protested, in the sense of what has inland intruder operations got to do with 'naval' aircraft.
When FAA Skuas were used to dive-bomb German positions in the Dunkirk Calais area, there had to be on targets near the coast - because of a demarcation dispute with the RAF!
But besides, for intruder operations, two-engines were better than one (assuming the 'intruding' is done at night), and the RAF for that had the Mosquito and the Beaufighter.

Agree with Merlin. The Mosquito was perfect for that mission. Fast, heavily armed, twin engined, radar equiped.

Firely has promise, but there are other birds that would do the job. Now if they used them in the Pacific to intrude over Japanese held islands, assuming they were radar equiped, that might work.