I can recommend watching Threads to get some idea of just how grim things would probably have been in the UK had there been a war at that time.

http://www.imdb.com/title/tt0090163/

NB Threads, although it depicts an absolutely devastating attack on the UK (~90% dead within a few years), actually uses a rather optimistic attack plan - a real attack would actually have been far worse.

http://en.wikipedia.org/wiki/Square_Leg