Lots to consider here, but if the journey is on A-roads i would suggest you look at small motorcycles rather than mopeds. Modern twist and go mopeds pretty much all have small wheels which drop into potholes quite easily – not really a problem in town but out of town they can be easily missed on a dark night.
In terms of actual models I know two people who do this and take very different approaches.
1. Spend a bit of cash on something from the big manufacturers, maintain it well (More spendy than you might think.)
2. Buy a brand new Chinese copy, do the bare minimum or maintenance, bin it when its first MOT becomes due.
Cost probably about the same in the long run.
You won’t go wrong with a Honda CB125F, and it will retain some value.
or for less cash the Lexmoto range are well regarded.