Forget the concept of "rolling"/going completely around until you learn to come back up on the same side as the dump and/or just want to practice or play.

In real life paddling, we almost always know when we are going over, try a brace or scull and still go over. That leaves us best set up to come back up on the same side we went down on. Do all your initail learning on going over and coming back up on the same side. It is easier, your are already in the best position especially if you have been sculling. You waste time, energy and lose position trying to get to the opposide under water.

If you are already sculling, just keep sculling back to the surface and then finish a roll up from the sculling position. Much easier, more natural.
Randy