How will the puppy travel in the car? I would have at least 2 people in the car, 1 driving and 1 able to concentrate on the puppy if she needs reassurance etc.
We picked up the puppy as a family, he traveled in the foot well of the front passenger seat so I could give him reassurance but he just slept! We were only 20 mins from home though.
You'll need to think about pee and poo stops for the puppy, safe places where she can go to the toilet on the way home. Have supplies in the car for accidents. We had puppy pads in the foot well, plastic bags for soiled pads, spare pads, baby wipes etc.
You also want to think about offering the puppy water when you do pee/poo stops, so you'll need a bottle of water and a bowl.
I'd left a blanket with the breeder that was left in the puppy crate so it smelt of mum/siblings when we took it home but the breeder also gave us a toy that the puppies had been playing with.
When you do get home, let the puppy explore if she wants to. Don't crowd her or make her sit on peoples laps if she doesnt want to.
My pup took himself off under the kitchen table and went to sleep for a couple of hours.
You'll get to know your puppys signals but make sure you take them out whenever they wake up. You might need to stay outside for a while with them. If you leave a door to outside open, make sure it is propped open so it can't close on the puppy in wind etc. But bear in mind that just because the door is open, the puppy will still need to be taken out to learn where to go to the toilet.
The other thing, the first few weeks are tough. My puppy only wanted to sleep on my lap (dont fall into this trap!!) and if left for 30 seconds got into mischief. I think DP would have sent him back for the first 2 months if he could.
Dont let them do anything that you won't want them to do when they are older, it might be cute as a puppy but just annoying when they are older.
Remember it gets easier. The more hard work you put in when they are little, the better behaved they'll be when they are older.
Oh, and always supervise the kids with the puppy.