Definitely mow to get them under control, or at least get some big hedge clippers and clip them low to the ground. The cheapest way is to cover it all with flattened cardboard boxes. You can usually get those free out behind the grocery store. These stay down better in the wind. Overlap them by a few inches. The rain will help to hold them in place, or squirt them with a hose. The darkness ought to stop the weeds from reseeding. The cardboard will break down slowly and will improve the soil.
The important thing is to keep the light out until you are able to plant it the way you want.
You could also use layers of newspaper, at least 6-8 layers, but you'd need something to hold them down, usually dead leaves. If you put them down just before it rains they might stay down better.
old boards and tarps work, too, but don't improve the soil.
And planting a clover or vetch, as he suggested, will compete with the weeds, improves the soil by fixing nitrogen in their roots. The seeds can be expensive, but if you know of someplace where there is clover, dig up the patches like you would lawn sod, including the roots, and transplant them, water them like a lawn. Of course, don't put the cardboard over them, but they are an excellent groundcover.
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Life goes on within you and without you - George Harrison