Actually, I think he said that parts of the West of Scotland get less sunlight of parts of the polar circle. Not actually the North Pole. Regardless, it's an issue. And now that I'm in the NW of England I'm still not getting much sun.
Anecdotally, I've experienced great improvements in energy, mood and general physical wellbeing since regularly supplementing with Vitamin D. When I read the study about the use of vitamin d with the chemo I was about to take, they recommended pretty high doses (probably 10,000 IU's) I just took "bunches" of whatever tablets I found at Asda. (I did read the packaging I just forget how much it was. I was probably taking about 5000-7000 or so.)
Buying them at Boots is expensive because they tend to be just the RDA. I've got Seven Seas caplets that are about 1000 each. Very pricey to take a lot of them. I also take a calcium that has Vitamin C so I think I'm getting about 2000 or more a day. I'll be ordering from Amazon when these run out so I can take 5000 a day cheaply and easily.
I will say that when I was on the chemo, for which I never met a doctor and only nurses, they wouldn't discuss vitamin D. It's not part of the protocol for the treatment. (However, that hospital is now conducting a study on Vitamin D with the same treatment!) So, I just did it on my own. Sure, I told the nurse about it and raved about how I thought it was possibly responsible for my early positive response rate and lack of side effects, but she just went "Uh huh... that's nice."
GP's and so forth aren't going to go outside what the NHS tells them to do.
The important thing is that it's harmless. Unless you have one of a few rare conditions, it's hard to reach toxic levels (which, unlike vitamin A, still won't kill you.) To reach toxicity you would need to take something like 40,000 IU's a day for a couple of months. That's twenty or forty high-strength tablets a day for two months.