Hi Tom. Thanks for that. I plan on using a 10mm or 12mm notched trowel for adhesive. Hopefully this will give me enough depth for adjustment. I have just measured the gap between some of the slabs that I layed out just to see them, and the gap is 20mm, erm smaller than this for there slabs just does not look that good but please correct me if this is just too wide. Also do I need a special cleaning product to clean off residual grout from the stone after grout has cured sufficiently or just old fashioned elbo grease.