Hi There,
Lovely to see a humble and normal folk are out there. So I'd like to help in anyway possible. A lot of people like to tell us about they're huge amounts of money and act as if they are seeking advice! If they are rich good luck to them!
First of all. You don't need a degree. But a good level of English and brush up on the grammar.
My experience comes from non expat land Galicia and I have immersed myself into culture and language, plus worked at one school so far. I had a Spanish girlfriend and lived for 3 years with her and her family.
So the Spanish love the idea of learning English and love everything English. They are more likely to listen to English music than Spanish and in most cases, all have a foundation. I don't want everybody to know this lol but you can start by offering Clases de conversación. Not many know this but there are examples of people who started out like this and then move onto open their own academy.
Its not easy, working and living in Spain, you will find that Schools WILL take you on (with your credentials - sufficient). But wages are between 600 to 800 a month depending on whether the manager puts you up in accommodation. I earned 700 a month with a flat. But they get rid of you as quickly as they take you on!
My advice is - earn as much money as possible, it may have changed slightly in last year but you need about 5 and a half thousand pounds to open a bank account if you are going to become resident. So you need that and maybe a years worth of money. Because... everything is done by word of mouth, in Spain and if you do conversation classes you need to get around the bars making friends and putting up adverts. (shops, bars, etc will allow adverts placed in windows for free. Also apply for jobs from home and someone will take you on. All the schools use facebook in main. So search the area find the schools and contact them via facebook.
This is a novel give me a shout if you need more info - website called tusclasesparticulares is a site full of English people doing clases indivuales. You can gain experience from checking this out.
Lastly I do stress that you learn Spanish - (the kids will swear at you and misbehave). Best way - the deep end! SO earn enough to live for a year then get mingling. I use duolingo to learn Spanish. Just keep your dream and goal positively secure in your hearts and you'll do it. I'm 3 years in now to my dream. It's a lovely dream. It's a project enjoy it. Through the hard times keep going. Be self sufficient and hard working. It's yours for the taking. So much to tell you, but don't want to make you disheartened or take too much on at once. But conversation classes - Scrabble and magazines. All the best. Remember there are approx 600.000 words the same in English and Spanish. Learn Castillano Spanish. (the main language spoken, if you don't already know all of this).
Jay