in all honesty, taking lessons in any discipline is a good thing. Some of that you learn in English translates to Western, and viceversa. Such as , sitting up straight and looking ahead, keepin your thumbs on top and your elbows next to your side, keepting your heel down, but not jammed down, having you leg under you , not in a chair seat, giving an aid and then stopping the aid when the horse complies, and on and on. Just because you have ridden trails in a western saddle, even for years, does not mean you know how to ride Western. you could take western lessons and still learn something that you may have missed in your career as a self taught rider.
I am not dissing being self taught. Just saying that not to assume that Western does not have compexities, too.