Ditto to what others have posted.....your dad is definitely being smart about it.
I could see, though, why it seems so much simpler (less work, less initiative on your part) to just go with the NHS therapist. I guess the equivalent to that in the U.S. would be like seeing a T in a clinic setting. Been there done that.

Firstly, the T's in the clinic I went to stay there for a year or so and then move on to better-paying positions or open their private practive (in most cases).
Also, everything of significance is put on the record, (I requested a copy of my records when I withdrew from therapy at the clinic).

While it's daunting to choose a T, you will definitely feel more in control of your treatment. I like to suggest to ask a friend for a referral. And go for a consultation, and see how you feel about working with that particular T. You can try a few T's to see who you feel most comfortable with.
Recently, I've had the ocasion to consult with 2 T's, both of whom were very highly recommended by friends and others. One of them is supposedly a top psychologist. Well, turns out I felt quite uncomfortable with both of them.

I, too, experience ptsd and other issues. I've had much success working with a psychologist who normally utilizes a cbt approach but has been utilizing mostly a psychodynamic approach with me, as this is what is most helpful to me.

Wishing you the best of success in finding the right therapist for yourself!
Do keep us posted, if possible....