And how much did the Emancipation Proclamation effect British opinions on the south? From what I've read, the Emancipation Proclamation helped dissuade support from the Europeans to the Confederacy by changing the purpose of the war to slavery and reminding Britain and other countries that support for the Confederacy would mean support of a slave based country. How true is this? Did Britain not support the South due to its support of slavery? Did they really consider supporting the South?
Well, to answer your question straight-out: not that close. Jefferson Davis and the Confederate government sent two "diplomats" to Europe to negotiate recognition for the south, yet they were largely ignored. This was for a couple of reasons. First, the British had/have centuries of geo-political expertise to draw from when it comes to touchy diplomatic affairs like the one that erupted in 1861. There was no reason to believe that the South would actually be victorious over the more industrialized and financially stable north at the start of the war, so while it was not seen as impossible, the smart money was on the north putting the rebellion down. Although Lord Palmerston was somewhat sympathetic (both personally and vocally) to the Southern cause, his government was not about to just blindly tick off an important trading partner by supporting the rebellious side in a civil war. In other words, the British had very little to gain by siding with the rebels, and a whole heap of U.S. (Northern) goodwill to lose if they did. It just wasn't a smart play for them. Second, what little influence the South could wield by threatening a complete stoppage of cotton shipments (which was affected by their own policies and by the Union blockade) was largely undercut by the famine that hit Europe right around this time. As luck would have it, the US Civil War broke out right at a time when Europe (and England in particular) was desperate for wheat, not cotton. Sure, cotton was nice, and was a lousy thing to be short of, yet wheat was what was REALLY in demand, and the North was more than happy to keep it flowing east, across the Atlantic. Early successes by the Confederates in 1862 and early '63 definitely gave a few British politicians a moment of pause, yet any traction these victories might have lent were quickly dashed by practical needs and Lincoln's own Emancipation push (which definitely had a negative impact on any movement in England to recognize the Confederacy). The fact of the matter was that the diplomat Davis and the Confederates sent to England (James Mason) never got a proper, official audience with the government, which shows just how seriously the Brits took the notion of Southern recognition (not very).
[Sources: Bruce Catton, 'Mr. Lincoln's Army'; James McPherson, 'Battle Cry of Freedom']