joe wrote:
Thanks for all your advice folks. I'll give them a spray with gyphosate,
leave for 48 hours, turn them over, burry them at least 6 inches deep and if
a lawn springs through my newly planted garden I'll tip my hat to nature.

I would leave out the gyphosate, I turned of earth with grass to a depth
of approx 6" and it didn't grow through.

IMO chemicals are to be used as last resort not first choice

ff.