Plan for putting new lawn down after previous tenants

Hi Guys,
The previous tenants layed down a plastic sheet over the garden (23 feet by 27 approx) and put loads of sand on top of it for their back garden beach party which was about 4 years ago.
Since then, weeds have obviously grown through and made it look a mess. Its also causing the local cats to use the sand as a litter box which is obviously a health hazard to my 14 month daughter and pregnant partner.
Ive managed to get rid of alot of the weeds myself, although not all as there is still quite a few brambles left.
What I propose to do, is painstakingly shift the sand to one corner while ripping up the plastic sheet under neath and disposing of it. Im then going to use the sand, which is now a sedimentary mix between soil and sand with grass etc growing out of it and use it to level the rest of the garden.
Im then going to buy turf to lay across the whole garden.
Its going to take alot of work for me, but I'd like to ask your input whether or not this would be the best course of action and that the turf would be fine on top of it once I'd rid the weeds and brambles?

 

Hi Azza

I sympathise with your problem - you've been left with a right mess.

But.....you're going to hate this.....I think you ought to get rid of all that sand. I know, I know, it'll be a lot of work but I doubt your neglected soil is so rich that it could stand being mixed with so much sand. It 's likely to make it even poorer and cause your lawn to dry out quicker. I also bet it's builders sand rather than sharp sand which is sometimes used as an ingredient for top dressing lawns.

Take your time, it's too hot and dry to lay a new lawn at the moment if you can avoid it. Early autumn would be better.