Nervous about driving

I got my permit... I am 20. I've always been terrified of driving. Always. It's a phobia. When I know how to drive to an extent. I can drive perfectly fine in parking lots. But I havnt driven on an actual road before. With other cars. Is it as scary as it seems?.. i have to pick my mother in law from the doctor tomorrow because she has to go under for a shot in her hip. I'm the only driver she will have... advice..?