> the average Brit did not care so much about Poland
After the Nazis invaded France, I expect that's true, yes. But before that the only reason for Britain to be fighting was over Poland.
> it's not like France was wrong to declare war - it was obvious that they were going to be next
No, it wasn't at all obvious. Hitler's stated purpose, going as far back as Mein Kampf, was that Germany should expand to the east. His decision to move west instead was rather sudden and surprised a lot of his own advisors. And didn't happen until eight months after Britain and France declared war (the intervening period was called the "Phoney War" even at the time).
After the Nazis invaded France, I expect that's true, yes. But before that the only reason for Britain to be fighting was over Poland.
> it's not like France was wrong to declare war - it was obvious that they were going to be next
No, it wasn't at all obvious. Hitler's stated purpose, going as far back as Mein Kampf, was that Germany should expand to the east. His decision to move west instead was rather sudden and surprised a lot of his own advisors. And didn't happen until eight months after Britain and France declared war (the intervening period was called the "Phoney War" even at the time).