Long drive alone...

There are few baby car cameras avaliable, if you would like to get one. I believe it's better to give every 45 minutes break, because your baby is still young. Have a happy and safe trip xx

It's completely normal to feel nervous about your first long drive with your little one, but you've already done the right thing by fitting a mirror.
The NHS advises that up to 2 hours at a time in a car seat is safe for healthy babies, so for a 3–4 hour journey, plan one stop before or around the 2-hour mark. Take her out of the seat for 20–30 minutes to feed, change her, and let her stretch before continuing.
I always try to plan a stop somewhere with baby changing facilities (and a coffee for me!). If possible, I aim for under 2 hours so that if we hit traffic, we're still within the recommended 2-hour window.
Try to leave after a feed so she's naps for part of the journey, use your mirror for quick, safe checks, and remember—if she cries, she's breathing. If she needs you, pull over somewhere safe rather than trying to reach her while driving.
You've got this!

I know little ones at times if lucky sleep in the car for a very long period of time! Hope your little one will. Can’t you take a train or bus? Less stressful and safer. Have a camera to monitor her movements. Or any family members you can take with you? drive safely and do take breaks 🙏 xx

I started driving my baby 2/3 hour distances when he was 2 months and it really helped if I fed changed and burped him right before putting him in the car. He would usually sleep the whole way and I had a camera on him. It made the trips a lot easier! And I would always just pull into a rest stop if he needed some attention. There’s no reason or rush important enough to not stop for a couple of minutes if needed!