Hi Rachie.
Living 1hr from NCL is fine, however I would seriously consider MAN because of the Long Haul opportunities and also a greater chance of being' kept on' in the winter.
Don't know anything about your condition so I don't know how it would effect your application.
Britannia do no carry out a medical, but you will need to fill in a medical questionaire honestly.
Good luck, its a great company to work for(...biased)