Hi Linda. I am English and have lived in Málaga, Spain for two years. The international House CELTA course is said to be excellent. It is expensive and very intensive, but well respected. Most larger "proper" schools in Spain ask for the applicants to be CELTA or Trinity certified. Some smaller schools may accept less, but you should check that out in the locality you want to teach. Personally I found myself private teaching work on a one-to-one basis here with Spanish, Danish and Bulgarian students by word of mouth. I have an adult training certificate gained in UK and plan to take the CELTA certificate in Seville early next year. Barcelona is too far away from me, but a vibrant and beautiful city. IH is one of the training providers I am considering. I know they are well known and respected world wide. Good luck with your dream, I hope it becomes reality.
Remember, it takes a little rain as well as sunshine to make a rainbow.