Grass seed comes in three grades, No.s 1, 2 or 3. No. 1 is finest grade, slow growing and lush as you said! But, and there is always a but, it is not hardwearing and wouldn't stand up to regular use, esp. children playing ball games etc. It is more for formal lawns. Grade 3 is tough and fast growing (contains more rye grasses) and will stand up to wear and tear but will need regular cutting. If your top soil is imported then it will need rolling to compact it and prevent hollows and settlement later. It's a big area to sow by hand but it can be done. Alternatively you could hire a seed/ fertiliser spreader from a hire shop pretty cheaply, looks like one of those push mowers and gives an even result. Either way mark out your lawn in to strips say 2m apart using builders line and pegs, this allows you to gauge the seed properly and ensure an even dispersion of the seed. When you've sown in one direction, peg the area out again in the opposite direction (at 90 degrees) and spread seed again, this will ensure an even growth in your new lawn. Tie some strips of foil or plastic onto pegs and leave them in the lawn to discourage birds from eating your lawn seed. Also you could try scattering some fine sand over the area to help disguise the seed. Be sure to keep the area well watered.