The good news is you'll be astounded by how quickly you can improve your Spanish living in a Spanish-speaking country. Before I moved to Spain, I used to pop over regularly for immersion courses - a month here, 2 months there- and even then I was amazed by how important immersion is to language learning. Speaking a language. Listening to it, all day long. Hearing it in the background, having to spit out that sentence if you want to buy a train ticket.

The bad news is that even after years, it still takes effort to keep my Spanish in shape. To communicate the way I want to.

I was whining to my Spanish teacher about all the time I spend writing in English (because that's how I pay my bills) recently. I feel the impact of all of that English on my ability to be quick and fluent and funny and well, me, in Spanish at the end of the work day.