Like all design industry jobs - people will judge you on your portfolio - not what courses you've been on. So before you approach anybody regarding a job I would get these ideas down on paper so others can see.
Look hard at was is already being done. Take some basic shapes (hand drawn or even scanned in) shapes of mx graphics or t-shirts, and then try and adapt these designs or create your own. The more you do the better/easier you will find it. Next thing you'll find is you'll have a load of work ready to be put in a portfolio.
I studied graphic design for 4 years, and have been doing it for a profession for 7 years. But i've met many people along the way who haven't a single qualification, but can still design very well.So don't always think that if you haven't studied it then you wont be any good!! Good luck. And this forum is a perfect place for showcasing ideas.