Here's the nuance that you don't seem to get. Germany and now Russia are the aggressors who started the war. Great Britain didn't just bomb cities on a whim. They were attacked.
Not that I fault them, but it was the UK and France that declared war on Germany.https://en.m.wikipedia.org/wiki/Declara ... rld_War_II
It would be the same situation as, say the USA, declaring war on Russia because of their NATO ties after Russia had invaded the baltic states.
At the time, Germany was clearly the aggressor, and knew full well what could happen in result of it's actions.
GB and France did declare war, but were so mentally and moraly unprepared that they didn't take advantage of the fact that almost all the German forces were in Poland to attack such a weak front.
Britain had been rearming since 1936, it was a bit like turning around a supertanker but it gathered pace, best example, the Luftwaffe failed in the Battle Of Britain as they were facing the world’s first integrated aid defence system. Which they did not know existed, their intel sucked.
Plans for conscription (which began in early 1939), as well as evacuation of children from large urban centers likely to be bombed, issuing to the population of gas masks if as in WW1 the Germans went there again, stockpiling of essential foodstuffs, rationing ready to go, the dispersal with new construction of industrial facilities for war production, the list is long before war was declared.
It would however take a long time to switch from the traditional small, professional Army to a mass conscription force, largely mechanized, some years in fact.
This was not the same for France, great political instability in the 30’s, military spending which was dominated by projects such as the Maginot Line, it did have one of the largest armies in the world, when Hitler came to power Churchill, one of the few voices in 1933 seriously alarmed by him, said ‘thank god for the French Army’.
Size wasn’t everything though, while Poland was being attacked the French did mount a limited, half hearted Saar Offensive, Germany had left its border with France lightly defended, but though France had plenty of tanks, it was really a defensive force, in both equipment and mindset of its geriatric commanders. Tanks good, tanks with every one radio equipped, much better. Guess who had them and who didn’t?
There were plenty in France then on the political extremes, the far right and far left, both had objections in the 30’s for really preparing for war.
Both UK and France had been traumatized by the huge losses of WW1, only one though had the war on their territory.
In 1940 outside of the US, France was the most motorized nation, forget the largely PR event VW ‘people’s car’, in terms of motor transport compared with population, France was ahead.
This however meant in 1940 the Germans had plenty of facilities to capture and use for refueling, something they seem to have forgotten the following year in even the Western USSR, never mind the Steppes.
I suspect that Russia was heavily counting on political divisions, which they have been prime movers in creating, inside Ukraine, which would have totally undermined serious resistance to the ‘Special Military Operation’, it had worked in Crimea, to a degree in the Eastern Ukraine too in 2014.
Knock over Zelenskiy, install a client puppet, the sort Ukrainians have made clear they don’t want more than once since 2004, however the Ukrainian leader did not flee, did not, like Stalin on hearing news of the German invasion, have what appeared to be a nervous breakdown and pissed off to his dacha for a period. (Try recounting that in Russia!)