The size of the tiles is dictated more to the skill of your tiler. Some tilers prefer smaller as its easier for them to get the fall right. Using wastes that are linear like the grates make it easier as its straighter for them to cut the tiles. Having round drains do make it harder to tile a fall in the floor with larger tiles but now days there are so many choices with the waste options for the shower spaces that it allows more choice in sizes of tiles. What size shower are you wanting to go? Will it be more like a 1000 x 1200 rather than the standard 900 x 900??

Thank you for this advice. The shower will be level with the floor and will be 900 x 1200 and we will use a linear drain grate and a frameless single panel screen of 1100mm.

I can't see why you would have an issue with tile size with this size shower and the use of linear drain grate. Check with your tiler before hiring and tell him what you are wanting. If he doesn't want to lay larger tiles then search for one that can lay larger tiles but also has references to support it. Good luck!

Great advice. Thank you

Use a linear grate. Our ensuite floor tile is 450mm by 450mm

At our other place the shower was walk in but had a tray under (lower than floor) with tiles cut as a pattern to a square drain.

The floor tiles matched our wall tiles . I think they were 300mm by 600mm for the bathroom.