Hello and welcome Bob and very good your grandsons have helped out.

Is this the back or front garden .

If you are not in a hurry to replant I would lay old carpets or newspaper or membrane to help supress.

And then keep digging out weeds as they come up .

When they are young weeds easy to hand pull out.

Hello and thanks for your reply, it is my back garden, since asking the question my two sons have said they will come round at the weekend and remove all the sods of earth with grass on them and rake the garden for me, again thanks for your advise much appreciated, regards Bob.

When you are removing grass its a better idea to trench the garden as you go and bury the sods upside down at the bottom. If they are about a spade depth down they are very unlikely to grow back and they will rot down and improve the soil. And you don't have the problem of removing the layer of grass either. If the grass is so near the surface that you can't rake it then it will certainly grow through again. Putting carpet or heavy black plastic down is a sure way of killing everything off but you will need to leave it in place for at least 6 months. I tamed a neglected piece of field that was to be turned into an allotment very successfully like this and it was full of thistle and willowherb. Nobody could pretend it looks pretty while you're waiting though.

If you're prepared to use sprays. Use Roundup available in all garden centres DIY sheds. . One application will kill all grasses.Make sure you don't get it on anything you want to keep as it's very effective.