IDK whether you need data and voice or just data. Also, if you're planning on calling the UK from Alaska to chit-chat, you ought to reconsider that and you should also be aware that outside the cities/towns cellular coverage may be limited to non-existent.
In any event, I suggest you explore gci.com which is the 'real' Alaska telecom provider and T-Moble esim which might fit the bill, you'll have to decide on that. Of course, while you're at sea, you ought not expect much service and you certainly won't get much on the run down to Vancouver.
https://www.t-mobile.com/support/plans-features/t-mobile-esim-app