“There is a strong social norm in the UK that women do and should do most of this stuff ”
I agree. When I lived in the UK it was shocking to me how many other parents didn’t really divide up child rearing and household duties or share authority over them. It seemed to me that the women had all the authority. The mum decided the school, clothes, meals, bedtime, screen time, the play dates/friends, discipline/punishment and also what household chores were to be done, when and specifically how and the father was expected to just defer to her authority. But the downside was that with the power came all the responsibility. So women were constantly (and it’s here on this thread!) groaning about how useless their partners were at doing things correctly (to their standard) or not knowing what the meal plan is, etc.
If you want men to share the responsibility, you have to relinquish the control over it all.
And even in the OPs case here, her DH didn’t make any mistakes. The doctors receptionist booked the appointment wrong. He told her he needed a double appointment for two children and the receptionist only booked a single appointment for one child. But the prejudice is so strong that the OP and most posters are assuming that it has to be the man’s fault.
If it had happened to the OP, can guarantee it would be a post about receptionists at GP surgeries getting appointments wrong.