My house and bathroom are small so space saving is critical. The original old bathroom layout has a small square shower and a separate half bath, with an even smaller basin right next to the toilet. It was claustrophobic and the half bath was only used for storing cleaning stuff. When we renovated, the bathroom was gutted, keeping most of the original plumbing points. Though we are not "bath persons" we decided to have a shower over (normal length) bath with frameless swing glass screen. From past experiences, I find it easier to clean a shower-over-bath than a fully tiled shower area, or one with a shower base. When visitors with young children came to stay, having a bath was handy. Combining shower/bath gave us room for a long vanity with plenty of bench space and away from the toilet. It now has ample of space in the middle for changing and moving around each other. Shower-over-bath definitely is an efficient use of small bathroom space.

1500 & 1800 is a bog standard (generic) bath size. What's the size of the bathroom, 1450 x ? and where is door and window, existing layout.... Most of my clients still prefer a bath in their houses. Even with a shower screen over bath. A renovation of existing bathroom with bath/shr/toilet/vanity in same positions may be all you need.

Aluminium does under go oxidation, although it is white. Unlike iron oxidation which is orange. If the tile is designed for use in a wet area it is probably coated or anodised to prevent white oxidation. Check if cleaning will be a hassle (risk stripping the coating).

Looks great, nice work! I'm still not 100% sure about the bath in shower area! I love that it essentially allows a bigger shower area within the bathroom footprint, but maybe its a great option for renovations but not so much for new builds?