Hi MaryB. I think the Jorvik trike was mentioned here before, but certainly there is a long discussion over here...
https://forum.cyclinguk.org/viewtopic.php?f=23&t=136989&hilit=Jorvik&start=15
...were it my money I’d go for a Pashley Tri-1 as being of better quality. Upright trikes are big machines to start with and I’m not sure that folding will make a huge difference.
just to check... have you ridden a trike before? They are a very different experience from a bicycle and any bike riding skills you have need to be put on hold on a trike or you will rapidly find yourself in a ditch! Whilst trikes are entirely stable that’s only when stationary and when moving you do need to take account of gradient, road camber, etc. That said, it very quickly becomes instinctive.
Low stepover height isn’t quite so crucial as it is on two wheels, as you can hold on the brakes, put one foot on the nearest pedal and step on without worrying about ending up in a tangled heap on the floor.
In forums like this the word “tricycle“ is more commonly associated with recumbents; the Tricycle Association website and forum is of the upright trike persuasion but more into racing than utility.
Keeping an eye on
eBay might yield a high quality bargain such as a Mixte frame Ken Rogers or Bob Jackson machine. Between my utility Pashley Picador and my Ken Rogers Clubman, it’s the Ken Rogers which is in fact the easier of the two to ride by a long way.