The Best the Anglo-French could hope for is a stalemate until either Russia or the US were to enter the war.
I think they had a chance to win,they were hoping-planning-expecting ...a cheap war :no big fighting :Germany would be defeated by an economic blockade .
that's a BIG simplification and exageration . Intelligence did not decide the outcome of the war. Ex:Enima did not cause the German defeat in the Battle of the Atlantic (how much UBoats were sunk by Enigma ? and it is very questionable that,without Enigma,the Germans would win the Battle of the Atlantic) One major reason the Malayan Emergency was a success,was that the communists had no,or few support,outside the Chinese minority .
There is an overimportance put on the Spitfire, it was a great airplane, but the Huricane was the backbone of the British fighter force and truley made the biggest contribution to the battle of Britain. The Hurricanes shot down many more aircraft in the B of B than the Spits, and they shot down the bombers who were so destructive. The Spitfires did provide a lot of the protection for the Hurricanes though and in that since made a huge contribution. In reallity, Britain probably did not have enough Spitfires to commit in sufficient numbers to make that big of a difference in France. On the other hand, much of the supplies the British were using against the Germans after Dunkirk was American lend/lease stuff and even Churchill knew without the US production capacity Britain could not wage the war it needed to to totally defeat the Germans.
There wasn't much Lend-Lease stuff in Britain post-Dunkirk, nor during the BoB since that particular bill/act wasn't passed until spring of the next year. 1941 was the first year of L/L "stuff" from the US, and the first shippments were mostly food and petroleum. I think the first "warplanes and tanks" were delivered to the MTO North African theater. We sent a lot of "military" things to the Brits, but only by sidestepping our neutrality act in a fashion. FDR declared a great deal of our surplus small arms and field guns (in storage) to be "scrap" and sold it to US Steel as scrap, who in turn sold the stuff to British purchasing agents. I believe that was again gotten around with the second 1939 Neutrality Act wherein arms could be shipped it to Britain in their own hulls under the "cash and carry" rule. At least that is what I have gleaned over the years, I might be wrong on some of those legal "dodges", but I'm not wrong on the lend lease goods.
Let's not forget the inteligence gathered by the French Resistance. With out the detailed info of the fortifications, troop placement, etc. D-Day would have been a lot worse. I read where a French architect had draw very detailed scale plans of the whole Normandy coast.