extending the garden

We started a veg patch in our garden about six years ago, the land had been rough pasture land prior to this. Even after six seasons, if we dig over an area and and leave it, an excellent crop of docks, buttercups and other "field" weeds quickly pop up, admittedly not as much as our first season but still enough to be annoying.
  We have managed to purchas a 1/2 acre field next to our garden (again rough pasture land) and want to extend our veg patch into part of this. What I'd like is some advice on getting this into shape for growing, would getting it ploughed be a good idea? or will this just bring years of weed seeds to the surface?, or the other option might be to mow it right down, cover it with cardboard and lay 6 inches of compost on type, a sort of no dig system to stop the masses of weed seeds in the ground constantly germinating as we've had in our original patch. Perhaps theres another way we could try? just looking for a good soloution  to the problem

It would be a lot of compost. I believe Charles Dowding gets lorry loads in from green waste recycling sites, so it may be worth investigating that. Much cheaper for huge volumes I would think.

Even if you are going no dig, ploughing might be a good option. There will be a million weed seeds anyway on the surface and it would break up the soil and get some air into it.

You could also try planting through weed membrane in some areas or if you can’t get enough compost.

I don’t know your thoughts on weed killer, but a one-off spray before ploughing would definitely help with killing the roots of buttercups and docks.

I'm in favour of the no-dig approach so as to minimise the number of weed seeds that you'd bring to the surface if you dig. As long as you do an initial cultivation to get the ground aerated it should work.

Rain forests or even deciduous woodlands have a very different soil profile.  They benefit from years of decaying organic matter shed by trees and little foot traffic by humans or large animals.

Pasture land gets some manure but also a good stomping from the beasts grazing there.  You can make really deep no-dig beds on top of it and grow successfully, but I think Gunner’s plan of weed kill, rotovate and then do no-dig will yield better results.

https://smallfarms.cornell.edu/2021/07/pasture-soil-compaction-a-slow-but-stealthy-thief-of-pasture-productivity/