Getting garden levelled and seeded -what do I need to know?

I am moving into a house with about half an acre of gardens. The ground looks like a filed (I think it is called "scrub grass"?). It is mostly level and drainage seems to be good.

I want to get the garden turned into a lawn and am phoning around to get guys out to give me quotes.

What sort of things should I be aware of so that I know what I am talking about (and so that I can tell if they know what they are talking about!)

Thanks for any help you can give me.

the grass should be sprayed (to kill weeds), cut, rotavated and seeded before the end of september so that the seed will take. after it is rotavated it needs to be lavelled with rakes and stones removed

Make sure to confirm what is meant by 'levelled' had mine done, and left a slope of about 1.5 blocks over 20 long....!!!!!!!!!!