Ok, here we go - the UK was more prepared for war than any other country at the start of WW2 (apart from Germany of course). We were the only country in the world to have a completely mechanised army and the only country in the world to have a fully integrated air defence system (i.e. radar and fighters to attack what the radar saw).
The tactics used by the British Army at the time were, unfortunately, not good enough to counter the Blitzkreig doctrine used by the Germans, however you’ll find that the US also suffered some heavy defeats from the Germans when they first entered the war (look up Kassarine Pass). It’s a fact of life that Generals from armies that won their last war prepare to fight that war again. The Germans had lost their last war and came up with a new plan that no one expected.
The British did see war coming, the Munich Agreement was signed because Chamberlain knew that Britain was not strong enough to fight Germany at that time. By the time Poland was invaded in 1939, the RAF had re-equipped virtually all of their squadrons with new aircraft (particularly the Spitfire and Hurricane that would be so important in 1940). The radar system was now fully funtional and the mechanisation of the army and the training on the equipment was also complete.
I doubt we had 100,000 spare troops to send to France in 1940, those we had spare, we did send. Why would 100,000 troops have made any difference anyway? The French army in 1940 was the biggest in Europe, the British and French combined outnumbered the Germans. We were beaten by far superior air power and land forces organisation, not by numbers.
Why would we paratroop every man we had to Berlin after the Battle of Britain? All that would have happened is that the whole army (without any heavy equipment, which couldn’t be paratrooped) would have been surrounded and wiped out - look what happened at Arnhem, and that was onlt a couple of Panzer Divisions, not the whole Whermacht. That’s even if the transport planes would have survived all the way to Berlin without being hacked from the sky by Flak and Luftwaffe fighters.
editted to add - feel free just to quote the bit about Kassarine Pass and then accuse me of anti-Americanism. See? I’m even helping you find the three words from half a page you need to quote now.