I think your email is fine. I once texted T before an appointment and told her there was something going on with my daughter and I feared being in my appointment and my daughter called. I asked of she would mind if I left my phone on because normally I would not because it felt rude. Her response was that first of all it is my session and of I needed to it was fine. Also, she understood that her clients have lives going on outside and that our children always come first. If a client is regularly getting calls or is texting it is a different story. However, I have only gotten a text or call a few times from my daughter, I quickly tell her I will call her after my appointment. My daughter lives out out of agate so doesnt remember my schedule