Martin 66,
Your info on UK gas supplies is completely wrong. I did a quick bit of googling to get some figures, and this looks like a decent link.
So firstly we have over 3 months of stored gas at the beginning of the winter drawdown period, but that storage can only be withdrawn at a certain rate - as it's a long term store. So I don't know what they've got in the way of emergency storage - but the on demand short term storage seems to have about 10% of the capacity of that one, so I'd imagine that's where your week's capacity figure comes from.
However, we draw 40% of our gas supply from the UK bit of the North Sea. And that's from multiple platforms and pipelines, which makes it pretty robust.
The linked page doesn't show it, but iirc our next biggest source of supply is Norway's bit of the North Sea.
We then have several LNG terminals in the UK and so are able to buy liquefied gas from the US and Qatar, amongst other places. This can obviously be bought at short notice should we suffer a supply interruption.
As I remember Russian gas via Europe is probably the smallest component of our supply mix. You are correct that most of this comes from Russia, although there are supplies coming in from Libya as well I think. Also there are 2 main Russian pipelines - as there's Nordstream through the Baltic which the Germans and Russians built in order to be able to bypass Ukrainian supplies in case of disputes.
It also bypassed our allies in Eastern Europe, but belatedly the Germans showed concern about this, and the EU's common energy policy means it's now connected up in a grid so that supply can be shuffled around to help those countries closest to Russian gas - who naturally are most reliant on it.
Because of Russia's unreliability Europe is also investing in more LNG capacity, so that gas can be bought into this network, if required. Many other countries have higher stocks than us, partly because it makes more sense to have smaller capacity pipelines and store locally, but also because they don't produce 40% of their demand from domestic sources.