Hi Dinah,
Friends of ours purchased a small Finca with the intention of setting up a small Equestrian Centre, They submitted plans for the Centre that included a House, general opinion was that they were wasting their time, but after many months (maybe years), much form filing with numerous visits to Tarragona and god knows where the plans were passed but with many conditions mainly timescales for the completion of work.
It is possible to get planning but be very sure about the advise that you take as most seems to be open to individual interpretation and wil change from area to area. Good Luck  ;)