Did most people predict a UK/France victory or German victory? How about among military experts? How likely did people think was the chances of the US or Soviet Union entering the war against Germany (as opposed to war against Poland or Japan)?
Interestingly Gallup polls had been established before the war - polling both in the US and Britain - and the ones from 1939 can be found here albeit it's a bit badly formatted:
http://ibiblio.org/pha/Gallup/Gallup%201939.htm
Two key points emerge however: First, the widespread belief in America that France/Britain would win the war; which in fact may have contributed to the low US support for entering the war (The French/British are gonna win anyway, so why get involved?).
Secondly, there was a staggering 80%+ of Britons who wanted the Soviets as an ally. It was not necessarily reflected as a position in the government however.