[mdjlucan]

 What's the recommendation one My allotment as I got quite a bit of weeds and grass I need to use a safe one  so I can dig it in when she dies thanks

[New shoot]

If you use any of the glyphosate based ones, they kill the weeds and the roots, then become inactive in the soil.  I use Resolva, but there are others.

You will need to leave the weedkiller to travel right down to the roots.  That takes a bit longer at this time of year, so wait 4-6 weeks before digging in.  If the grass is long, it is best to strim it down, before applying the weedkiller   

[mdjlucan]

 Where can you buy It

[New shoot]

Any garden centre or DIY place with a gardening section will sell glyphosate based weed killer.

[mdjlucan]

Thanks