Tell your H that the plans he made without consulting you will not work because you have a vacation already booked for yourself and D. (Don't tell him he was included) Tell him you're giving him fair warning so he has time to change the plans. Tell him in the future that he needs to consult with you first as to plans of this nature before he finalizes.
You can convey this in a business like tone without it coming off like you're angry. You're in control of this now and your H gave up that right when he made poor choices. Let him feel a few consequences.
Tell the gym that H gave the wrong address and phone number and give them his.
