I enjoy threads like this, and discussions about the various ways we could meet a catastrophic end. It's better to understand the consequences of a nuclear attack than bury your head in the sand.
There's nothing that you can do of course if a nuclear weapon detonates nearby. But if you are on the fringes, keeping calm and understanding basic concepts can help to keep you alive. People assume a nuclear explosion is all about vapourisation, mutants roaming around and so on.
Fallout affects people over a wide area, and making plans for where you would shelter and how you would survive in the short term is a sensible thing to do. Where in your home would you be furthest from exposed surfaces (roof, windows, walls)? Do you have the basic food, water and heat to stay in that place for a few days or weeks? Do you have some toys there to keep the children amused? Where will you dispose of bodily waste? Do you have the basic skills and tools for survival, and for fending off people who were less-prepared than you?
I always think of it like buying a fire-extinguisher: the best scenario is that I never use it, but if I need it I'll be glad I bought it.
I highly recommend The War Game, available on Amazon of course. It's a 1960s docu-drama which focuses on the outcomes of a nuclear attack, for the survivors of the initial blast - firestorms, social breakdown, martial law, etc.
To all the people who are frightened by this thread, I honestly feel that a nuclear attack is not something you should be overly worried about. I think you are far more likely to be killed in a terrorist attack, a car accident, by a stroke or cancer for example.