I have difficulty in imagining Putin launching a nuclear strike against NATO members or anyone else, for the simple reason that he has nothing to gain by doing so, and runs the risk of losing a great deal (despite what the BBC programme would suggest)
He would surely be much better served by utilising his vast conventional forces to seize whatever he likes/needs? What could/ would NATO do faced with an enemy on this scale, on the ground, and with a seeming tolerance for attrition well beyond our own? We stood back in WW2 until the Red Army hard worn the Wermacht down. Would we be willing to take them on with our dramatically reduced military capability?
Having been a lifelong supporter of our nuclear deterrent and our military, I do now find myself wondering whether Trident is a blind alley, and whether we should be spending the money on our conventional forces instead.
The nuclear threat I fear would come in a suitcase from some terrorist, not from Russia.