Hi Rachid,
I am starting our big veg area too. I did my back in concreting the polytunnel legs so yesterday sat on my old jcb and leveled out the big heaps of topsoil I had previously dumped all over the area.
This is on rough pasture grass and the soil has many stones and rocks.
My plan….
Level(ish) out the top soil heaps (including awkward huge lumps of tough grass).
Scratch around with a fork over the whole area and pick out the bigger stones and rocks.
Black plastic the area using the stones to hold it down.
Concurrently make loads of compost.
In the spring drag the plastic along about 6ft and apply lots of compost and cardboard paths.
Plant this up.
Keep making compost and once I have enough compost for another bed, drag the plastic along again and create another bed.
Thats roughly my plan.
We live just down from an electrical store warehouse so each week I go there and take all the cardboard they have. It is becoming a bit of a liability at the moment as it is building up rather than being put down but it will get used.
Rob