Create a garden

So in my garden it looks like I still have a pile, mainly clay, overgrown with weeds. I still need to fill other areas of the garden and of course the terrace in between.

Now my question is, I would get a trailer full of material from the chipping site and then use the tiller to till the whole thing and level it out somewhat, what do you think, is that the right step?
With the goal then to further garden design

First kill (or have killed) the old weeds with glyphosate. I believe if you are not a gardener or farmer, you can't just get it and don't have the spraying equipment either. Then till, rake smooth, lay out

Glyphosate-containing products are still freely available. If one needs them at all, the dosage should be observed.

Not always use the chemical club right away. Depending on what kind of weed it is, it may be enough to till. Chipped material can be used. However, one should make sure that there is no plastic or anything else in it if possible. Spread and work it in. I would then, just to be safe, use the garden for a few years as a vegetable garden (potatoes and such) or as an ornamental garden with annual plants. This way, it is easier to determine if unpleasant weeds like [Giersch] appear, which can then be removed more easily than if you have shrubs standing and it shows up between their roots.

The plan is already to plant a hedge and sow grass... in spring.

The plan is therefore to till in chippings and topsoil, overwinter, and then finally level and sow grass in spring.

Hello,
should this be an ornamental garden or a vegetable garden?
Clay soil is fertile but in summer the soil becomes hard like concrete. I would first treat the clay soil with glyphosate-containing products according to the instructions. After the weeds (wild herbs) have disappeared, work in plenty of topsoil, sand, mulch with a large tiller to make the soil more airy.

Regards, Laura