The Northern Route is generally not done- the duty of care in the event of something bad happening to the receivers is generally given as a reason. This was batted up to AOC1 Gp and was his decision last time it was mooted.
UK-Lajes-East Coast USA generally gives the best spread of abort point airfields- would the FJ guys really be happy about diverting to Iqualit with 1000kg overhead?- and weather factors.
There hasn't been any UK MPA assets on a trail for a while
AFAIK- the new SOP is for the FJs have the handheld maritime radios, so can summon help if the worst was to happen. (no, really)
With tanker availability being scarcer than in the old days, quite often the FJs are trailed as far as the East Coast and deployment further west is unaccompanied.
WRT the Portuguese MPA crew "hiring themselves out" the UKAAR force regularly trails European air forces in return for AT hours.