I have experience in this group. I had to train hard for my Tri's and I know how it feels to be a beginner. I even swam in an event call Peaks to Portland, which is open ocean swimming, at the same time I was training for my Tri's.
I can teach any age swimming in this category. I just ask that you know the basic swimming techniques to keep you safe. I can teach you for however long it takes for you to get comfortable.