More for a wall than a floor but have a look at StoneMerchants website.
They have a large showroom and outdoor display area out at Rathcoole Industrial Estate.
If you give the lads and lasses in Outhaus a call or visit them then they may well be able to source what you are after or even have it manufactured for you.
They are very good at making custom/bespoke tiles for domestic projects.I have personally dealt with them and they are very good at custom made tiles and brick slips.