Q: Will I fail the drivers test if I use 1 hand to steer?

Yes probably!

Using 2 hands to steer is recommended. You can take your hand off the wheel momentarily to shift gears, fix your glasses or scratch your nose but make sure to put your hand back on the wheel after that. It is very important to grip the steering wheel properly with two hands as this is one of the main methods you are using to control the vehicle.