Spanish pronunciation is not too difficult. All sounds are also to be found in English language. The only really difficult thing is the rolling "r". However, everyone will understand you also without the perfect pronunciation of the Spanish "r", which makes Spanish even more sympathetic.
Now the big question, how different is Spanish from Spain or Spanish in South America. First of all, we can state that no matter what dialect of Spanish you speak, you will be understood everywhere. When thinking about your own country, how many different dialects are there and what actually is the general standard? Some of them may be hard to understand, however, it's still the same language.
One thing is of course sure, the differences between the Iberian and South America are bigger than the differences inbetween the Iberian or within Southern America. The Southern American dialects seem mostly to be more soft, they use sometimes different words and some minor grammar issues are handled differently. to give you an idea, we have taken sound samples from Central Spain and from Columbia to listen to.
The discussion about, what is the normative Spanish is held in Spain and in Southern America, as well. For Spain there is a common understanding, that the language spoken around Salamanca and León is normative. For Southern America, this is not actually decided. The most in common for the continent is the Columbian accent. In addition there is always the discussion, what is the most accepted accent, but also here there is no general truth. So, for us as non-native speakers, this all should not be too bothering. Most important is - to understand and to be understood, whereever we are. And this will be given with a bit of Spanish and some patience.
With this, we just wish you: Have fun!