I found a computer driven model that simulates texas holdem poker almost to the T. It’s not like playing at a real site though. At Americas Cardroom and most poker sites you can request free chips for free games. The games are cash games where you can come and go as you please. It’s a great way to learn. It’s probably better than the computer model game since you are playing with real players.
The Americas Cardroom game is below. You have to download the software and install it. After that look at the yellow circled tab that says play money. Click it and find a variety of holdem cash games you can play for free.