The Natural Philosopher wrote:

Triple that for ALL power, including transport and industrial heating
and domestic heating.

Double it for PEAK capacity..

Sounds plausible, but recent real data is readily available:
http://stats.berr.gov.uk/energystats/dukes07.pdf

I am talking *total annual power consumption of the whole country* -
around 160GW average..

It's surely somewhat irrelevant to talk in terms of power, when overall
energy consumption is what matters. (The power flux in the pipe while
you're filling your car up is about 8 MW, but err, so what?)

Or were you thinking about delivering all energy in the form of
nuclear-generated electricity?

--
Andy