Not the ideal way but at least it will make allow you to get growing and make it easier to pull out any that start to grow.
Brambles are hard to get rid of. The not only seed, but regrow from layering. I would dig out as much as you can and then rotovate, removing any more that you find.Rotavating and then adding manure to the soil will be adavantagous when finally planting and growing your crops.
where are you? i'll bring my cutters and fork
I have resigned myself to the fact that there will be a permanent spot for brambles at the bottom of my garden where the foxes live. I have managed to erradicate them from the rest of the garden and provided you cut off any long tendrals before they touch the ground (which is when these root and form a new plant) they are pretty easy to keep under control. As well as this they are excellent for attracting butterflies and bees and provide stunning fruit ...