I'm having the same idea/dream as you have. becoming an instructor of some sort that teaches or shows other people things about nature, outdoor sports, primitive skills, etc.
Can you tell me something more about yourself and why you want to be an instructor?
The way I see it, is that if you really want to be an instructor you must have been orientating yourself on the subject now for many years or months and you know exactly why you want to become one. of course you have participated in some courses and maybe gave some courses or workshops. you know what interests you about the profession and what doesn't. and you're almost sure wether this outdoor thing is something you want to do professionally or just as a hobby. finally if you have come this far it's no problem at all spending money as an investment in your future as outdoor instructor. If most of these things apply to you, then you would not ask the question you have asked on this forum.
Don't get me wrong. Above might sound a bit harsh or unfriendly to you. but it is a realistic view of how I see it. And I'm defenately not trying to demotivate you in becoming an outdoor instructor. in fact. I think it's great that you know what you want to do in the near future and that you're motivated to do so. it's also great you're taking action in achieving your goal. keep it up!
I do think though that becoming an outdoor instructor without investing any money won't get you where you want to be. No education is free. Schools and universities also charge you, if you want education. where the money comes from is a diffirent question. So I don't think it's weird at all that outdoor companies ask you participate on their courses first to become an instructor afterwards. they earn cold hard cash with that to keep their companies running and they know what and who you are before they take you in as an employee. for you it's an investment that can be earned back.
Please tell me more about who you are, what you do and what it exactly is that you expect in a job as instructor. Taku adventures might be something for you, but... it costs money. a lot. of money. Yes, that is the downside. about 6000 pounds. The upside is, that it's an education agknowledged by the government. and it might be a ticket to solicitate to outdoor companies all over the world. check it out. it might help you.
http://www.takuadventures.nl/can/egids.html
I hope that you find your way to becoming a guide or instructor. They company is dutch and some things might not be translated. if you need any translation or more info or anything else. just pm me or post it and I'll see what I can do. good luck.