@2stepsback — I actually suggested professional lessons to help ease the stress you are feeling AND to help the stress your father seems to be feeling.

If he is pressuring you, he is likely stressed. And if he is stressed, he might welcome the chance to hand over teaching you to drive to someone else. I realize that maybe it’s expensive and that’s always a consideration for people.
My only other suggestion would be to “focus on the driving, not on the pressure you are feeling.” Focusing on the pressure can be a distraction which doesn’t help when we are trying to learn and use new skills, whether it’s driving or cooking or doing math problems.
Siblings are often good at making life more difficult…If he’s bothering you by asking, “When will you schedule your test?” perhaps give him some brush-off answers... “How is that your business?” “Why do you need to know?” “When I’m ready.”
Yes, you are feeling pressured. Focus on learning and practising the skills. You don’t need to hurry or rush through them. Take the time you need to think. Practising driving is how we learn to make the different “maneuvers” automatic. If staying in your lane at the right speed is hard right now, practise those — with your mind on doing it and on watching the road, and not on “Oh my gosh I need to learn this and I’m tight for time and my brother is being a pest and…and…”
You can do this. Bit by bit you will learn!