Big. The garden itself is an outer edge corner plot, 130ft down the longest side and roughly 100ft along the back; the lawn covers roughly 2/3 of that and I want most of it gone.

I've certainly got the space for composting, I've got areas where the grass clippings and plant cuttings etc get chucked anyway.

Glyphosate might be a better idea, I did wonder about that - but, I have to be careful of the plants as well as I have rhubarb and raspberries growing at the edge of one bit of it, and the back portion (there are three distinct areas within the lawn, not physically separate though) has three fruit trees growing in it.