Not sure if you ever found a good English lesson barn in the area. We recently moved to the area about a year and half ago found a couple established schools in the area we really liked. You may want to check out Cedar Hill Farm closer to Waxhaw, and Leg Up Equestrian closer to Fort Mill. Both have great programs with really good instructors and established reputations. I think Leg Up Equestrian is more youth focused and Cedar Hill offers more opportunities for outside showing and has nicer boarding facilities. 

We have a teen daughter and school age son who both ride now. We started my daughter in lessons and my younger son in a couple summer horse camps which was a great introduction to riding for him. I think you'll find the horse scene in the area very active and growing. 

It's been a great experience for our family overall. Alternatively, If you are looking for a smaller barn with a private instructor I think you can find many more barns in the area that could be suitable for you. Just check around and see what's best for your family. Everyone I meet in the horse community has been very friendly here and I'm sure you'll find what you're looking for   

Best of luck!