Clearly a lot of filler will be needed to cover up those "errors".
I rephrase my original question ~ why are you plainly not fitting this new shower where the old one, that you told us you had taken out, used to be?
Ah, I'd forgotten your question Hound...
The old shower was a stand-alone 'cubicle' shower with a steam generator and other useless paraphernalia built in... It was shite so I took it to bits and dumped it up the tip...
Unfortunately, because it was free-standing (you could literally move it around the room) the drain pipe in ther floor didn't match up with any other shower tray on the planet... OK?
Another 'feature' of the cubicle shower you will note is that the taps are just a few inches from the floor - another obstacle that I will seamlessly overcome...