Don't worry, Be Happy! You are going to Spain!
I just returned from Spain and it was apparent to me that most tourist orientated establishments did a pretty nice job accomadating English speakers. You will run into countless English speakers on holiday (or vaccation depending on their origin). These anglophones can help steer you in the right direction. BTW, most large tourist sites offer tours in Spanish, and English so don't fret. A good phrase book and the willingness to try it out will endear you to the non-English speakers, and will enable you to see the nation away from the tourist herd.

Buen Viaje!