Not a bad talk, but it really just drives home the point that the majority of the problem with unsustainable energy consumption is simply idiots who neither know how much energy they use nor even care. This guy is a physicist, and admits that he eliminated 50% off his heating bill simply by reading his meter and setting his thermostat properly.
If that's typical for a physicist, the average person doesn't really stand a chance.
As for the rest, it comes off as very anti-biomass, which may make sense for Europe but makes no sense in the Americas or Africa. Consider that I can heat my house with 1/4 acre of miscanthus. But consider also that my house is smaller than average, and better-insulated than average, and in a warmer climate than most of Europe and in a country with 1/8 the population density of the UK.
Really, though, no one should have the slightest pity on the British for wasting all of their fossil fuels on warfare and empire building rather than planning for sustainability. Like "oh you overpopulated your little island with its miserable climate and consumed all your resources attempting to subjugate half of humanity and supporting a failed welfare/warfare state? Tough shit, deal with the consequences."
In general, Europe is fairly screwed on the energy issue unless they can expand renewables into Northern Africa in a major way or, you know, sacrifice their quaint brick siding and learn to insulate their ancient houses properly. The British are just double-screwed, and it's really only karma catching up to them for harboring the world capital of ponzi economics criminals that they actually bought into their own bullshit and believed that finite resource consumption could go on forever. Oops.