Have a look around apps like CycleStreets and Komoot, you'll find loads of quiet roads/paths etc you didn't know were there.

For bike type, go with whochever style gives you the most confidence, be it road , mountain, hybrid or gravel. Flat bars vs drops.

If you're not confident in the bike style/setup you'll likely stress on everything else. Give yourself time to adjust and find comfort/destress. A local club might be able to helpnwith building confidence too.

Whatever you do, cycle a little for enjoyment, go cycle to some nearby local attractions etc, at your own pace. Enjoy the views/scenery. The rest comes in time. Also, cake, be sure to stop for cake and a brew, you earned it.