Hi
I am glad someone posted up the Alzheimers Society as they are great, and also run a helpline and will send leaflets.
My mum got it really early and had symptoms well before 60. Things that stood out were inability to deal with foreign currency on holiday, when she had always been an astute businesswoman. Also very erratic driving. Another thing was getting into a panic doing things she had previously done well, such as cooking a meal.
Getting a diagnosis was hard as I think she suspected she had it and delayed going to the doctor despite family encouragement. This was a shame as she missed out on a lot of time where the medication available would have helped her.
My advice would be try and see the doctor asap, even if you have to connive with them and go under some other pretext. Also, if your dad does have it, try and get informed and discuss his wishes for future treatment.
It's a hard conversation to have. We did not have it as we did not know enough about the progression of the disease. We had family agonies when it came to time to decide whether she should have artificial feeding via a tube, as different people thought different things, and she could no longer express herself. (She did receive a tube but that's another long and complicated story).
Good luck.