> Who would win in a war? Russia, easy.

Really? Russia has not even done all that well against Ukraine, a much smaller economy.

What sort of war? I agree Spain could not successfully invade Russia, on the other hand Russia could not invade Spain either. No working aircraft carriers so their air force would be operating from very distant bases (even if they were allowed to pass over the countries in between), limits on ability to land large numbers of troops, etc.

> no longer part of the EU, but was better for both when they were

I do not understand why you even mention that as the EU does not have a military, NATO is relevant and the UK is in NATO.

Its a matter of opinion. I think the UK is at least as well off (growth has been similar to comparable economies like France and Germany since Brexit) without even seeing the long term benefits AND the EU is better off as the UK was a major impediment to the political integration the Euro zone needs.