I don't want to burst your bubble but no, you can't teach without dance experience. How can you teach partnering, demonstrate steps as a man and as a woman and most importantly teach proper technique if you haven't experienced it yourself? I have been dancing for nine years (I'm in my 50's as well). I am a good solid silver level dancer and I just feel confident now teaching beginners. I understand their difficulties because I experienced them myself. Also, I know how dancing should feel and how a man should lead a figure without pushing or pulling. Also, I can switch back and forth from man to women.I have had about 650 hours of instruction. I compete in standard.
Have you had any experience dancing with a partner in close contact? Ballet as a child is a joke. Seriously, it has absolutely no bearing on ballroom. By all means start dancing ballroom, it is never too late but you won't be a good teacher until you have real lessons from a qualified instructor and can actually dance around a room with a partner.