Any concrete slab or prepared stone slab will crack on clay, you need at least 3" of concrete beneath it. If and when you get round to the walling and path, dm me your number and I'll tell you exactly how to do it, it only appears to be a small area and well within DIY boundaries.
Tx! For future I want to build some retaining walls and steps, unfortunately no £ ATM.
They did not build any retaining wall near the garage so underneath a platform it's just a slope. Sigh...
There are lots of grey basalt chunks left in the garden, those seem pretty tough and I'll use those as steps
I can imagine standard pavers just crack ..