You can do it directly. Ring up the Cambridge Flying Club and book a flight in their Tiger Moths. Should cost you a fraction of what one of the Red Letter Days would. I did a couple of hours with them a few years ago and, despite the fact that the Moth is a thoroughly miserable creation in every respect, I thought the club do a very nice job with things. Your dad will have a ball!
Then take him on down to Duxford and watch his head explode!
I'm guessing you're at Mildenhall? I was. 100th CES, 95-98.
Pitts2112