No letter about dating scan 2 weeks after booking appointment

Currently 10 weeks and 4 days pregnant. My booking appointment was at 8 weeks and 4 days and the midwife seemed to imply I'd receive a letter about our dating scan a few days after that but there's been nothing.

I've now been on hold with the ultrasound department for over an hour and they haven't picked up 😔 am I being insane wasting my whole afternoon waiting? I just really need as much notice as possible as I have a toddler and I remember how clear they are about not being able to bring children to the scan, so I will need to arrange childcare and if it's too short notice that won't happen so I'll be alone.