I would recommend that you watch 'Joanna Lumley in the Land of the Northern Lights' which is being repeated on BBC2 on Monday 29th December at 6.15pm. An excellent programme.
Bob - it might not be the answer you were looking for, but if you watch the programme you will find that she travels to various places to see the northern lights, so it should be of interest to you!
I'm going to Tromso in early Feb. The trip is sooo expensive it doesn't really matter how much the beer is. Not much point in going on a cruise ship as it'll be dark most of the day. I've watched the DVD that Hurtigruten put out but they show everything in daylight. We're taking a sleighride out into the wilderness to hopefully see the lights. as it needs to be as dark as possible. Can hardly wait.