No space for a scan

I’m considered high risk pregnancy - I’m 42 and my first baby and this baby are measuring small. I was supposed to have a scan next week, but it turns out the consultant forgot to schedule it and after 3 days of calling, I managed to get through. The receptionist said they are fully booked and they can put me on a waiting list (along with 50 other people) but I might just be seen. She transferred me to the midwife, who said I need to be seen, but it doesn’t sound hopeful. It’s making me anxious as my daughter’s life was saved after having an emergency c section off the back of a scan. My question is, if they don’t find a date, what can I do- private scans never want to reveal the growth details (I’ve found) . Thanks!