I doubt you're going to find it easy to find those to be honest. You could try taking a picture into a Topps Tiles store. They used to do a tile-finding services. But it'd be a case of them needing to know the name for them to enter it into their systems. They sometimes have the odd tile a few years old in their stores somewhere across the country and can bring it up by name. But I'm not sure 11+ years they'd even have the same staff in the store now that they had when that tile was on the market. Worth a chance though perhaps.
40+ is a fair area. Can you perhaps section it off and use another contrasting tile and make it look like it was meant to be like that? Do you have a picture of the full area that has the damaged or missing ones? We can perhaps come up with some ideas for you...?