both Britain and France were favorably disposed to the USSR ... in a ham-handed, slow boat, limp wristed kind of a way .... even after Molotov-Ribentropp there was some misguided notion of signing a non aggression pact with the Soviets. Remember, the time window you speak of, the USSR had yet to play the territorial gains card it had won from Hitler .... the 3 Baltic Republics, and parts of Romania.
... in September, 1939, Stalin's 'position' was seen as less aggressive and purely defensive.
In early negotiation with Britain and France, Stalin had offered to 'contain' Hitler ... for the price of deploying westward into Polish territory.
Request was denied at the time .... but that's what he indeed did in September, 1939.