lisbet, you have a great advantage, living in Spain already, which makes your TEFL course choice a lot easier. I found that my boot camp style is only suitable for young people, anyone over 30 would be struggling. My advice would be to take a longer course, maybe over 12 months, as swatting over the 12 verb tenses plus 50 teaching ideas, which you are expected to know in your final exam, is not easily done over a period of a month. Don't forget, there are other things you need to do, as well, not just the grammar. I do emphasise that I am talking about my particular course, not generalising, as I am aware that all courses vary quite a lot. So do your research, you are not in a hurry, and search all sorts of forums for real experiences, don't rely on the course providers' websites. I noticed that the one I did had a web site which didn't allow for ex-students' comments about the experience - now there's a surprise.