We are out of range anyway, and also any strike would have to pass through either the US or China and Russia and the rest of Europe. No danger to us directly at the moment.
If miraculously the entire North Korean army did manage to get to us and land on our shores, then frankly worrying about Cameron's cuts would be the last thing on our mind. Even before those cuts there probably wouldn't be enough to stop such a large army. The only reason this isn't frightening at all is because it's also never going to happen. No way the NK army will be able to get here, or even in a position to be able to land.