Hi Little Red
So sorry for the circumstances that bring you here but I'm sure you will find lots of support, empathy and information. Everyone on this site will know how you are feeling - most will probably agree that this is perhaps the toughest part when you have a bit of a diagnosis but no facts or treatment plan in place to calm your fears. It is really tough but, as Chris says, it sounds as if the cancer has been found early so there will be lots of options to manage the disease and keep it in check.
Mad to say don't worry of course, but there are plenty of men on this site whose PSA was in the 100s or even the 1000s when they were diagnosed and they are still going strong.
Do write down all the information you receive tomorrow and then you can update your Dad's profile. That will help forum members to give you good advice about their own similar experiences. You can also contact the specialist nurses by phone, email or live chat - they are wonderfully knowledgeable and supportive.
Good luck tomorrow - do let us know how you get on. Will be thinking of you.