You'll struggle, but theoretically it can be done. Assuming the door is central to a long wall, you could have a 900 wide x 700mm deep shower tray to one end, a loo at the other (around 650 deep) and a small wall hung cloakroom basin centrally. But there will be very little space to stand outside the shower.

It is possible but tight. You will need a low projection toilet and small knees, a cloakroom sized basin and a shower that is no deeper than 700mm with either a curtain, inward opening door or sliding door. With careful shopping you may be able to find one that is 600mm.
You can make the room feel a little bigger with a big mirror, a wall hung basin with no pedestal and clever storage- you can get some cabinets designed to fill the space between wall studs.

Thanks Jonathan and P&P for the very helpful advice - it seems it is just possible. I have also looked at the integrated toilet/sinks which are quite ugly but do save some space...

Good idea about the floating hinged door. Are wet rooms more expensive to install though? And will the concealed cistern require a thicker wall?

And yes the sliding door is to the room, as in your above plan

The short answer is yes, the wetroom will cost more as they are a bit more involved but it helps to shop around and to find a fitter experienced with the process. There are off the shelf tilable shower trays that sit flush with the floor that might make it a little bit easier, with the walls and remainder of the floor being tiled as normal. In-wall frames with cisterns come super slim - approx 90mm - 120mm. Even if you have to build out a little to accommodate it this could still be worth it to have the wc off the floor.

In short, yes, its possible. The key is to use compact toilet (you can google it) and small sink and 70cm wide shower. A more precise design depends on the exact layout. Can you send a sketch?

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As long as shower is small, and doors install in right place there should be way to do it.