Learning Spanish is a great idea, always better to try and struggle through with the local lingua instead of the hilarious attempts of many at mime or hand signs or mumbling and indeed, you will meet many people who speak only Spanish so some Spanish is a good thing and even a courtesy. Having said that, you will meet pilgrims from Japan, Korea, China, Australia, New Zealand, India, Poland, Hungary, Italy, Germany, Denmark, Norway, Sweden, Holland, Belgium, France, Ireland, England, Spain, America, Canada, Brazil, Argentina, Mexico, and many more - would you like to guess what is the Lingua Franca? Right, English.