Eleanor, you absolutely must bring your 14-24mm! It performs excellent on my D800 (not the E). It's supposed to be reasonably water resistant, but be careful with that huge front glass.
In Lofoten the period with midnight sun is from May 28 to July 18. During that time the whole sun is above the horizon. At midnight, the sun is in the north, so you need to be on the outer parts of the Lofoten islands to see it. The villages Ramberg, Eggum and Uttakleiv are perfect locations. I do not know how long the ship will stay in Lofoten, but hopefully they will arrange bus trips for you to see the fishing villages and amazing scenery.
The best times of day are very early morning and late evening, or even night. Depending on the weather of course.
The first photo attached is taken half an hour before midnight, in June, in the village Ramberg. The second is from the village Unstad, a very special place. It has become rather famous now, attracting surfers from all over the world. Maybe I am in Lofoten when your ship arrives, do have a date for when you will be in Lofoten?
Good luck, hopefully you will have better weather than we have now - 2 degrees C and snowfall/sleet.