Posted: 24/02/2015 at 05:45
I would burn the whole area, best you can with a gas burner or the use of a few bales of straw. This will kill off any weeds seeds and clear the area. Once that is done you will be able to see where the perennial weeds (Brambles and others) start to grow. then use a Vitax SBK Brushwood Killer (or similar).
There is no point rotavating the land until you have removed all the perennial weeds as you will just chop them up and they will come back 10X worse. dig them out by hand or use a weed killer once they start growing. You may need several applications and this will take time.
It's better to get this sorted now than have brambles growing through your lawn later, when it will be impossible to remove without destroying the lawn.