@blossum  I have got my first one coming up at the end of June. I went through the public system and they have dates for my U/S and Mammogram exactly one week before I see surgeon so they can go through results with me. Also the breast care nurse will sit with me while seeing surgeon to explain things if I don't understand anything.  She always does, then takes me aside after to have a chat about it all and any concerns I might have.
Seems a bit odd having seen the surgeon/ registrar before the scans.   Sounds like you have drawn the short straw with a cranky BC nurse.  I hope everything goes okay and definitely proactive is the way to go. 
I've got an endoscopy booked at the end of this week a bit concerned about as never had one done before. ( I gag even taking tablets. ) 
Big hugs and hope all goes okay. xo