How would scrapping our nuclear weapons benefit a country like Britain?

I was thinking about the late Michael Foot the other day, he came out of a background of westcountry liberalism and moved into socialism (very similar to me, my father campaigned with Dr David Owen in plymouth in the 70's). I have never really seen the point of nuclear weapons and while I am not an "inveterate peacemonger" I don't see what Britain would ever have to gain by dropping a nuclear warhead on anyone, even if they were our aggressor, but I am keen to hear your opinion.