Hi, we've a hardstanding just outside the back door that's a combination of uneven concrete and paving slabs from many years ago. It's solid but not level either but does allow surface water to drain away on to the lawn borders (that's fine). Was wanting to put a little patio area over the above concrete/slabs using something like Driveway Grid Tiles. Would like to place some decorative paving stones over the grid which could be simply interlocked over the grid tiles?. The uneven level could maybe be sorted with some timbers or feet under the grid tiles?. This would all allow surface water (after a bad rain storm etc) to still follow it's chosen route. Would want to put gravel in the grid tile holes as normal. Gravel should also keep the mice etc from living underneath the patio. The Only need the patio area around 1.5 X 3 metre in size for me and the good lady. Were both in our 60's so easy to DIY would be ideal please. Thoughts?.. Thankyou