What the two of you can start doing now is going around to gun shops and asking to handle guns that are behind the counter. Mind the etiquette - don't point at anyone or out the door, trigger finger off, ask before you try the trigger...
Note if you like how it feels in your hand, if your dad's thumb can already reach the controls without shifting (mag release sometimes needs a shift) which sights you like better, how short or tall it is for carry, wide or thin.
See if there is a range that will let you shoot several good candidates. Label and keep the groups - which did you shoot better with?
Go to gun shows and hold as many as you can - don't be shy its perfectly normal. Maybe hand sanitizer is called for come to think of it.
If you've been looking at budsgunshop.com or other online stores remember you'll have to pay a store an FFL transfer fee - anywhere from 15-30 dollars. And shipping to the gun shop/ lisenced individual that would receive it.
These days carry of "compact" guns is not so bad with hybrid style holsters IWB. A sturdy belt typically wider than a dress belt if you can is considered standard too.
To look up later: Theiss holster, shielded holsters, old faithful holsters. Crossbreed. Thebeltman.
My carry semi-auto S&W M&P40c although 9mm would do just fine. Their newest (and somehow less expensive) creation is the M&P shield.
I shot the Glock 26 best at the range at the time but hates how it felt in hand. Wise choice? Only God knows!