Even to find a place that was very windy when the UK was 'calm' could require some pretty large distances.
I seem to remember the river Seven and Solway Firth were considered as being far enough apart that tidal generation would work. But it was tried somewhere in France, and it seems the idea stinks literally, and they had to modify their idea and only generate in one direction as it needs the tide to clean the bay.
The idea of pontoons with wind above and tidal below has also been considered.
I know my dad was in charge of a multi-fuel power station, part of the Shotton steel works, and it could use coal, coke, blast furnace gas, and coke oven gas, but steel making in Shotton has stopped.
Even on the Falklands, the diesel generators used the cooling water to heat the accommodation. There was at one time a British gas boiler with a sterling engine to use waste heat to produce electric, it seemed the problem was government rules, it did not slot into part L or something so was dropped.
The problem is time, be it a solar panel, wind farm or any other power station it takes time to get the investment back, and the government chop and change the rules too fast, so someone in good faith fits solar panels, and then 6 months latter they find they could have had them free with some government incentive, so their children say we are not doing it until we are paid to do it, as we are likely throwing away money. Plus the free panels are using inverters which don't include batteries, so the householder does not really see the benefit, and likely also too small, so they talk about how useless they are, and others are put off fitting panels.
We have seen the same with heat pumps, I have lived where they were the norm. The small window mounted units if they failed, it was just exchanged, and it heated and cooled, room by room, so rooms not used not heated or cooled, but the government grants stopped that type being used, and the type used got a bad name, mainly due to poor fitting, so people have said thanks but no thanks. The government meddling has done the reverse to what was intended.
Like the selling off or privatising of the electric industry, so we still have a government controlled sector of the electric industry but not our government but the French government.
Rant over.