I think the point of touring on your own at least is to go/see/do wherever and whatever you want
This! A thousand times this!
I suppose I had a gradual introduction to cycle touring just buying more expensive gear as I discovered what I really wanted/needed and felt that my abilities justified.
Which ever way you approach it, just enjoy it and don't worry if anyone else thinks your cycling plan "sounds crap"
That gradual introduction sounds perfect and mirrors my own experience.
Again, the idea that the tour is
yours.
Perhaps I'm reading it wrong,
@CentralCommuter but it seems that you have an idea of what "bike touring" should be. I'd suggest trying to drop that, at least until you've tried it.
Some of my "tours" have been cycling out to a friend's farm for some winter camping, doing a 90km route to camp 10km from my front door (I needed a night in the tent, a day on the road, but time was limited and I needed to be home early the next day).
I've chosen themes to follow for shorter trips - wartime cemeteries was one, rivers or canals another. Instead of taking the car or train I've used the bike (packed up) to visit friends in other cities. Overkill? Certainly, but still touring.
If travelling solo, the world really is your oyster! Go. Stop. Turn here. Eat there. See this. Avoid that. It's all what
you want to do! Wonderfully liberating!
As regards will a saddlebag do, why not get together the stuff you'll need and actually see if it will fit?
Apart from everything else in relation to hybrid v roadbike, I'd imagine a roadbike is more limited in terms of where you can go. Since I tend not to plan in great detail, I don't have to worry about surfaces, I can flake off my notional route if that over there looks better.
No reason that you can't try out both, is there? Or use one for one trip, the other for another?
Maybe for a first tour look for a friend with a bed and plot a route to them. Different route home, if possible. Then ask yourself what have you learned.
If you're not aware
https://cycle.travel/ is a great route planner, especially for touring. It includes accommodation.
And CGOAB (mentioned above) is a great source of inspiration and learning. Under Locales you can drill down to Stirling!
Good luck!