Peter,
You've posed some interesting questions, and I have to confess that I won't be able to answer them fully without some research.
There are most certainly power links between England & Scotland. The U.K. "National Grid" system was developed back in the 1920s/1930s based on a network of 132kV transmission lines around the country (with later additions of 275 & 400kV lines). I would guess that there has been an England/Scotland link since at least that time, although there were probably local distribution networks that crossed the border before the National Grid was set up.
For Britain to Ireland, I seem to recall hearing about an undersea cable being commissioned a few years ago. I would think it connects to Northern Ireland rather than the Irish Republic as the distance would be shorter. I'll see if I can track down some details for you.
I know there has been a cable under the English Channel linking us with France for many years (at the narrowest point, only 22 miles of water separate us). I'm working purely from memory here, but I believe it went into operation in the 1950s and operated at around 2 to 3kV DC. The combination of the 1-hour time difference and the fact that the French tend to work and eat at different times to us means that our peak-demand times are different, so it benefits both countries.
I'm not too familiar with northern England as I've only been up there occasionally, but I know the main London-York line runs up through parts of Nottinghamshire and Yorkshire where there are quite a large number of major power stations. It's one of our big coal-mining areas (or at least it used to be) and also a region of heavy industry (e.g. world-famous Sheffield steel), so the concentration of generating stations there makes sense.
The last figures for electrical generation in the U.K. that I can recall were around 70% conventional coal/oil/gas-fired stations, and about 25% nuclear. The balance is hydro-electric schemes (mostly confined to the mountainous regions of the Scottish Highlands and North Wales), wind-farms, etc. The latter has attracted quite a bit of attention in recent years.
Most of our nuclear stations are located on the coast, but I think you'll find that the other inland plants mostly use local rivers & canals for cooling. We have quite a network of old canals that were one of the mainstays of transport of goods in Victorian times before the railways took over.
For comparison with our neighbors, I know that the Republic of Ireland has no nuclear power, but France gets around 75% of its needs from nuclear. I have a feeling we talked about this in here a few months ago; I'll see if I can find the thread.
I know there has been talk about trash recycling for power over the last few years, but I have no idea of percentages used for energy etc. Again, I'll see if I can track down some details.
By the way, I've never been to York itself, but our National Railway Museum is located there and it's reckoned to be very interesting. Did you see it?
