I would start from scratch, you have to rip 1/2 this stuff out anyway to find where the damage is, you can't just cover it up so might as well get nice new bathroom and maybe fix some other things you don't like.

You can't rebate the channel into the plaster board, a whole lot of waterproofing issues there... and you will need both structural silicone to fix the channel underneath and regular silicone to waterproof on the outer... it sounds like in order to achieve the floating glass look that you're after, then you'll need a shallower channel or thicker tiles :/

Or if budget allows, why not have both an overhead shower rose from the ceiling and a wall mounted handheld shower head. Hubby prefers overhead shower (and I think most guys do as they don't really care if their hair gets wet) but I don't wash my hair everyday and wanted a wall mounted handheld one, so as we couldn't agree we settled for both with a diverter mixer tap. P.S. the ceiling shower rose we got can be slightly tilted and I think most of them do so you can have it at a bit of an angle. P.P.S. if you can't get both then I would go with a wall mounted handheld shower head as it will be much easier to clean the shower area, can't imagine the practicality of cleaning with an overhead... good luck! :)

Hi Katrina, Polymarble is preferable over acrylic as it’s self-supporting as well as resilient to the demands of everyday living. Additionally, an added benefit is that it has a quality feel and is solid under the foot. Fontaine Industries offer frameless shower screens with these bases. The middle image you found from google is actually from our store. https://fontaineind.com.au/oxley-frameless-shower-screen-900mm We have two locations in Melbourne, Hallam & Niddrie. We’d be more than happy to help you out and answer any questions about concerns you may have.