Hi

sorry you are going through this difficult time. 
 

I can only speak of my own experience, I had an endoscopy on a Thursday and received a call on the Monday asking me to attend an appointment the next day where I was told the biopsies showed cancer, I had a CT scan a few days later, I met my consultant the following Tuesday. 
 

It does seem a little odd that a scan has been requested without you being told why. It's normal practice when test results are in they are discussed at a weekly meeting between the whole team who decide the next steps if any,  it's called a multi disciplinary team (MDT) mine generally meet every Tuesday morning and patients are brought in that afternoon to discuss.  Perhaps the delay in your dads follow up appointment points towards it being non urgent, I hope that is the case for you. For me communication from my team was excellent every step of the way, maybe you can speak to someone on Monday morning and tell them your concerns? 
 

Best of luck x