How should I go about taking the on-the-road driving test?

I'm in my 30s and I'm still trying to get my driver's license. I took 4 hours of driving instruction a couple of months ago, but he told me that I would need to purchase more hours since he thinks, even though, I've improved, I could take 4 more hours and use the company vehicle. I was thinking about just taking 8 hours since he may change his mind how many hours he said I needed and just take the on-the-road test once the last 90 minutes.

Now, my dad has a Honda Odyssey that I have been doing a little bit of driving, but he doesn't want to add me to his insurance because since I'm a new driver his rates will increase. So I have no other choice, but to take more driving lessons and use the company car or rent a vehicle.

Now, he's telling me he'll check and see how much his rates will increase, but I told him that I would pay the difference, but I don't believe he's going to add me since he changes his mind a lot. He doesn't want me to pay to take the driving course, but at the same time doesn't want to add me because even if I take the driving course, I'll just be restricted to driving fleet vehicles until I can get my own insurance.

Unless that 4 hours is the same day as the test or even the day before it, so you will still have the confidence, then 4 hours, days prior to the test is nothing. He just wants your money.
If you already have the Instruction Permit, then tell your father to take his son driving a few times a week to get you the experience, so you can take it with confidence.
If you don't have it then get your nose deep into the manual & take the written test for it.

I took my daughter up to the huge parking lot of the community college each night for a week straight before her test. We brought all sorts of things with us to lay down in the parking lot to represent curbs, cars, street corners etc.
Because everything was on the ground & so low you can't see them out the windows, so it forces you to use your mirrors.
She practiced all sorts of things. Backing up straight between items, backing up while turning between items, parallel parking, and more.
The morning before her test she not only drove to the test, but we took a drive in the total opposite direction for breakfast, about 20 miles. Yes she drove.
By the time we got to the test area, she had driven 60 miles or so, and had all the confidence in the world, and it was like she drove every day.