Lawn Weed with Lawn Feed

I'm never going to be able to keep a decent lawn with the problems my area has with very poor drainage, fairly heavy clay, and constant weeds blowing in from the surrounds of the golf course. As the front lawn is just 100sqm approx I thought I'd get the local turf company to relay the area a few years ago, only to find that the ants loved it, so now I still get the weeds, but an uneven surface with little sandy hills in places.

The turf company put on Evergreen Complete 4 in 1, which I used for a couple of years, and have a part-bag left.
Last year my wife brought in another new bag of 4 in 1 which I used, and seemed to have even less effect than the old. I see that there's a subtle difference between the 2, and the newer 4 in 1 is in fact "Natural", which talks about preventing weeds, rather than killing them. Also I'd measured out and used quantities as per the 1st batch, i.e. at max 35g per sqm, whereas The Natural says use 40, but for best results use up to 70.

I've waited to apply until I could give it the first cut before which it's been too high, and now just want advice as to whether the older Complete is likely to remain usable - it's perfectly dry and granular - so I can try and kill as many of the new season's weeds as possible, and maybe use the Natural I have left in autumn, and applying at nearer 70 per sqm may have better results. Or just go out and buy an actual lawn weed-killer and forget the above?

 

If I had my way(married for over forty years so will never happen), I'd lose the grass totally. Too much work involved making it look good. There's loads of alternatives for the space...but as I said, that's just me.

 

I never get too bothered about "grass", but if you want a perfect lawn then probably your old weed a feed will still work..

They are banning weedkillers left right and centre so the modern stuff is less likely to be effective.