There is a rapidly growing Spanish population in Edinburgh so you are not alone! A good option to meet people is by sharing a flat or staying in a hostel when you first arrive (at least until you settle). Quite a lot of the culture revolves around meeting in pubs but there are other options. For example: http://blog.theforest.org.uk/savetheforest is a nice meeting space where a very diverse group of people hang out.

Thanks so much for the advices! I've saved that website to my favourites. Sharing a flat is what I was planning to do. I hope I'll be lucky with my flatmates. :-)