Relocating and at a total loss, please help! (Barcelona)

Hello,
I am looking into moving to the greater Barcelona area next Spring/Summer and would really appreciate your help in terms of orientation.
I will be moving with my 4 year old son; people have suggested the Sant Cugat area but it is too expensive for me, so I am looking for more affordable alternatives. I prefer small towns, the countryside to the beach areas, and need to be near good schooling (in English) for my son. As I live alone, an international expat community would be wonderful... I will be making several trips to the area over the next months to "scout", but if I could hear back from people who have made the move, in similar conditions, I would be very grateful.
I have also been suggested Tarragona, which I will also explore. I have chosen Catalunya for a number of personal reasons, proximity to family etc, but for now it's just an open book and I'm lost on where to start.

Help would be MUCH appreciated. Thank you.