At the moment it's just a huge expanse of clay which hardens in the sun to look like a cracked river bed and is of a texture for making pots in the winter
i think you need to decide what you would like to use it for before spending any money. If you don't have it covered it will continue to be a huge expanse of clay! That's what clay does.
Did you use specifically soil or compost in your raised beds?
We bought in 8 tonnes of topsoil. That filled about 37 pallet collars which we are using as raised beds. we have thick weed fabric underneath. Under that, on top of the clay, is 10 years worth of composted material plus 2 huge loads of woodchip. We are covering it for long enough so that the woodchip composts and when we uncover it, if we ever do, the mix of the topsoil, and the composted woodchip and the dead weeds by then, should give us a decent enough non-weedy allotment again.
But we will only do that when the pallet collars disintegrate!
At home we also have clay but we run a no dig forest garden and so it only gets dug when a tree or plant is going in or coming out. Otherwise it is left. but that's after 12 years of adding compost on top. Our forest garden although small, consists of loads of perennial fruits and herbs so loads of material is left on the soil to compost in it's own time. We rarely have soil with nothing on it.
Do you want veg or flowers or trees?
with clay you get about 2 weeks in the spring and 2 in the autumn where it is of the correct moisture content to dig and plant.
If you cover with a foot deep mulch of say, woodchip, it keeps the soil moist, so when you want to plant something, you take the woodchip off from where you want to plant, then dig a hole, add compost and mix in, then plant the thing, backfill with the soil and compost mixed, water in well and then replace the woodchip back around the plant. In time it composts and improves the soil. It doesn't work so well with veg. Plus you need something to hold the woodchip back, which is why these things end up as raised beds.