I have some very persistent moss and clover, plus some other horrid weeds, in my lawn. My parents helped me treat is a few years ago, which helped, but the problems are back with a vengeance.

Apart from ripping it up and starting again, what should I do?

The lawn is 7 years old, was turf, probably cheap, and on good soil, but likely full of builders waste (the borders and patio were a nightmare to dig).

Cannot afford to waste my money doing the wrong things. Do not want a fantastic lawn, just a nice grassy, neat lawn with no moss or weeds, so my son can enjoy it more.