We have been playing around with this today and this is the layout we think we will go with. Due to solid floors and walls if we move the loo we need significant boxing in. My app has limited selections of items but we will have sanitary ware in these locations, we think!

Initial thought is that 74x74 is a very small shower cubicle. In my work I’m currently involved in specifying a bathroom refit and we have rejected the proposed 80x80 as we feel it’s too small. We’ve asked for 80x100 instead, or more ideally 90x100. But one can only work with the space one has of course. Avoiding the step up is doable, provided the waste can be sunk low enough. Depends on the structure of the floor. It’s often much easier/cheaper to go with the raised tray. We’re having a new shower room at home and the floor is being designed so the tray can be sunk down so it’s almost level with the floor. But that’s the advantage of installing in a new section of building! Angie

Following with interest! I have something similar that needs renovating, but in an apartment, and no window - around 3500x1200. Personally, I wouldn't swap the loo and shower (I always prefer a loo to be near a window (!) and wouldn't lose a window ie valuable ventilation for the sake of a slightly bigger shower, but obviously it depends what's important to you). Maybe half tiling the non-shower areas is an option? The bathroom fitter may have clever solutions for fitting the right size tray into that width. Good luck!

Is option 1 the existing lay out?