The garden from scratch

SC am I tright in thinking your "private water supply" is in an underground pipe coming from a spring or similar? Is the blue line drawn on one of the top plans the ditch? Is the ditch particularly water retentive/reliably damp? If so you could plant it up with water marginal plants, flag iris maybe? Pop a willow near by on the corner of the plot in the wooded bit?

Water supply is coming from the burn up the hill a bit . It will run through a pipe eventually. All we’ve put in place so far is the flow through filter tank. The blue line is a ditch we dug, trying to help dry out the bottom of the plot. We’re getting it dug deeper & wider as it definitely seems to help and has constant running water. It runs into the burn that runs down the side of the plot.  I was thinking flag iris . We’ve got lots growing here. I’ll collect seeds from them this year.