I have my practical driving test on tuesday and my next lesson is on wednesday. I dont have use of a car and need to practice, so I thought they do mock theory why not practical and I dont have a credit card so cant pay.

You would need a full car simulator – with proper car controls, sounds and control feedback, and all round vision.

Mercedes-Benz have one in Germany, and one or two other part-simulators have been built for specific tests.

Your PC wouldn’t have the necessary controls (you don’t drive a car with a keyboard and a mouse), nor would your screen give you all-round vision. It wouldn’t be able to provide you with any useful experience.