Tracey

For a penny less than two dollars ($1.99), I have found the Ipad app: Speak It! just right. It is the most basic type and talk app out there with no real bells and whistles.
It only has 4 "free" voices: two male and two female. The "American" voice "Ryan" sounds exactly like Stephen Hawkins. The "British" voice: "Graham" sounds a little like the early Beatles, much more human. You can type up phrases and little speeches in advance and save them. You could even type it some of them for your Dad in advance.
I only wish I had discovered it earlier than last week.
OCF is working on an Ipad app but it's not out yet
Oh, and ignore the "bad" reviews on the app store since they all complain that you really cannot import text from books or documents or emails for all practical purposes.(the developer overpromises but hey it's two bucks) For those you would need an expensive application/software.
Bonus: Speak It! is basic and runs on my Ipad one, while many of the newest apps require an Ipad two or three or four since the Ipad one cannot use IOS 6 due to it only having 215MB Ram.
I don't know anything about Touch chat, but for two bucks, Speak It! is worth a try IMO.
Charm