Great, thank you! I'll have to have a look for general garden images as well - I've no current relief, though I may have a drop I can utilise when I remove the concrete we inherited, but I reckon I can build it up about a foot, drop it in a foot, and that's the required depth. Then I can just build up a bit more to provide height for a trickle (our geology round here tends to slabs, which is handy).
The previous owner did stone carving in his spare time, so we inherited a lot of odd-sized cut rocks that could be used for the building up, and then the nice local stuff (nicked off the fields - if Farmer Barleymow spots me, I'll tell him I'm keeping them out of his combine knife) can go where it will be seen.
Coronavirus may be evil sh*t, but we are spending much less at the mo, so the garden projects may get spurred on.
Adrian