Hello Seaclay, and I must say your clay sounds highly clay-like, compounded by being so flat and low-lying.
Interesting about the worms.
I do not have experience of worms not traveling into soil, in the way you describe.
This suggests one has to rely on cultivations.
However with the compost you have added and continue to apply, I am sure that plants will grow enough to help soil life in opening channels.
The growth of your plants will tell you how the soil is opening up and I suspect growth will be good, do keep us informed.
