In the central areas and at tourist attractions, people you deal with will speak English. The same is certainly true at international hotels, although the housekeepers not so much, so you call the guest services line or talk to the front desk in person for special requests. Some years ago I drove alone by car through rural Spain, staying in small villages, knowing only four or five words or Spanish without any problems. Younger people in Spain generally have learned English quite well in school and through movies and TV, although older educated people might know French etc. instead.

BTW don't be afraid to do the excursions on your own; you don't need to take a tour and be herded around with other foreigners and given bad expensive meals at tourist traps. Also the advantage of doing a night away from Madrid is that you would see Toledo/Segovia/Seville at night too, when these places are beautiful. There's a very pleasant culture of strolling in the evening, stopping at an outdoor cafe for a drink, and then proceeding to a restaurant for a late dinner.