Seems like the easiest thing to do might be make the whole window end a shower with glass partition, and move the sink next to the toilet. There are some nice examples around of windows in a shower, you just have to ensure you set the window up right.

I don't know what building codes apply where you are located, but here, you could not do what you are proposing because both the toilet and the shower spaces are too small. You would need a minimum of .8 M for the toilet space, and .9 M for the shower. Now, you could do a pretty nice sized shower at the bottom there where you show the toilet and shower, and then eliminate the tub entirely and put the toilet and sink on that wall. But you really don't have room for a tub and a shower here unless you can find a short tub that can fit across the room rather than lengthwise.

Thanks Williamsen and Hollysprings

Willaimsen- I think your idea could work. When you say "setting the window up right" do you essentially mean tiling the window sills? Do you have any links to examples of windows in a shower?

Hollysprings - our aim is to get rid of the tub al together.

If that's your aim, then you've got plenty of room for doing the shower across the bottom like I showed and then doing a nice sized vanity across the long wall with either the toilet or sink closer to the window. If you did the vanity closer to the window, you could do a half wall at the end towards the shower and that could shield the toilet from view from the door. Then the window wouldn't have to be replaced with a vinyl or fiberglass and most of that wall be rebuilt and waterproofed. You don't want a shower with a window without a LOT of extensive waterproofing.

Yes that makes sense, thanks. The problem will be moving the toilet (or more specifically re-routing the soil pipe). But perhaps we'll just have to take that on!

I don't have specific instructions, but here is a link with some threads here.

Hollysprings has some great ideas too, though they involve moving your plumbing. I think your best bet is to read up as much as you can on what you need to do for a shower window, then really think about the logistics of that vs moving plumbing.

Here is a link that might be useful: Window in shower

Thanks Williamsem, that's also good advice. We'll get stuck into some extensive research before doing anything. Thanks also for the links, they're extremely useful.

Someone just posted a nice how to on the recent thread about a giant window in the shower if you want to take a look.