I came across this which I thought was interesting, now the one thing I do know is that things never quite work out how those who lay out such scenarios expect.
My grandparents were bombed out, I remember the IRA attacks obviously ona much smaller scale and a very different time. Anyway it is not just the UK, look at what is happening in Ireland currently. Historically the UK has had to import food well from the Victorian period but now we can add energy and most other things so it is a much more fragile system, the recent situation in the ME has shown that, I know people who will be lying back from London in a few weeks and I semi jokingly mentioned they need to keep an eye on Jet fuel availability.