Hello, I am struggling with my driveway, it used to have 900x600x50cm flags on sand, to be fair, the vast majority are in a poor condition, and we basically just wanted to replace them. I am struggling to find slabs that are 50mm thick that I can afford as my local reclamation yards aren't stocking them, can I use a thinner slab to park a car on, and if I can is sand appropriate, many thanks