It is a good idea to rent and look around.

There are a number of different English communities in the Tarragona - Tortosa area if that is what you are looking for.

A few of these areas are:-
Many villages etc around Tortosa itself.
Mora region
El Perello region
Freginals/Amposta region
L´Ampolla region

These are probably the most English populated areas, so you may want to look at these, or avoid these ;)
I am sure other people will add places to this list that I have missed, or forgotten. Good Luck.