Creating a lawn from part of a field

I would like thoughts on the above please. The field/garden/lawn is uneven and has some couch grass in . I do not wish to rotavate the whole area as it's about 30 m square and thinking of killing/digging out the couch grass only and then getting a truck load - 20 ton at a cost of 15 per ton to create evenness  and a new seed bed for grass seed across most of the area. Any left over topsoil can be used in the woodland garden I am trying to create Cost is an issue as on a budget 

Many thanks
Julie