Proper spelling is *stirrup. You don't have to worry about it so much as long as you have a pair of boots or sturdy shoes that have a heel that is about 1 inch high. The heel will prevent your foot from sliding forward in the stirrup and getting caught. You can also get safety-release stirrups which, in the case of a fall, either pop entirely off of the stirrup leathers, or have a rubber side that comes off to let out the foot.
Another option instead of taking riding lessons is to take a friend or two who know what they are doing and go to a place that offers horse rentals for trail riding and the such. These horses are pretty much bomb proof and are used to all sorts of people and many types of riding styles (not so much riding styles, but rather are used to people who might have incorrect posture or are unbalanced or hold on tight or hold the reins too hard or too loose.)
Baby steps are you're best option, and I agree that asking your neighbors if you might help with them groom and tack their horses on occasion will really help you.