I have some plans for something related to taht, but since I haven't written them down myself yet, I can't reveal any details.
Because a major POD 40 years earlier is bound to have some sort of effect? Also, the UK was also a supporter of the Monroe Doctrine, and won't take kindly to France just playing around in the Americas. That, and the fact that, ITTL, Napoleon III just jeopardized the proto-Entente that was developing between the UK and France by helping the slavocratic CSA win its independence, while the UK was staunchly abolitionist.
It may have some effect, but not defiantly on the big, key events. The UK and France had clashes in Fashoda
The Entente didn't really develop until after Germany was formed. The UK's main interest was the protection of it's empire. They joined France and Russia against Germany because their colonies security depended upon Franco-Russian good will, far more then German. After Germany united in the Franco-Prussian war (which it is very likely to win, unless it's advisors in the American civil war prompt a major reform, that gets completed before the war) it was the major power and with Kaiser Bill 2 they were going to rub Britain the wrong war, looking for colonies, threatening UK market share, building a big fleet.
If you can use butterflies to affect these things, then a UK France clash would make sense.