Although some of the plans have been revealed before – including earlier this year the scripts that would have been broadcast by the BBC in the event of a nuclear war, instructing the public not to panic – governments of the period left nothing to chance, including the censoring of private mail.
The country would have been divided into 12 regions, each governed by cabinet ministers with wide powers, aided by senior military officers, chief constables and judges and based in bunkers. Other senior figures would have retreated to a central government shelter under the Cotswolds.
As was pointed out in this article on Soviet invasions of the rest of the world far from the state collapsing in the event of a nuclear attack, the people would presumably become more dependent on whatever state remains. The War Book emphasises this point.