It all depends on where you want to teach. The basic requirements are a degree and a tefl cert and depending on the school and country that cert can be online or not.

Where do you want to go?

It is not so much where I want to go as if I will have proper training to be able to hack it!? I definitely think that probably in-person teaching is tops above the rest, but I also think it would be better to have my certificate and hopefully job before going over. I want to know if the online course will teach me what I REALLY need to know to be effective? Or is it just a waste of money?

Some online courses (and some face to face courses as well) are rubbish and not worth it at all. Others are pretty good and will give you some good grounding in the basics of teaching. (ICAL is the best IMO)

Something like a CELTA with supervised teaching practice is the best but it costs a lot and, in my personal opinion, you get more out of it after a bit of experience and in that way you can really relate to what’s being taught. An online course is much cheaper but, like you say, it doesn’t do face to face. But, it is better than no training at all which is what I had in my first year!