Would you be prepared to give up the shower for a tub and shower? For the next five years it might be useful.You could remove the sink and shower and place the bath along that wall (with the shower fixture where it is)Hard to see space but could you fit a small sink in front of the window or next to where the shower was (again hard to tell your dimensions).....?

About your plumber saying "plumb layout is confirmed". That is a load of rubbish. It's fairly easy to move drains around (yes he might have to rip up some walls, but he can also do off-the-wall installations to avoid that). In a small bath proper placement is of the utmost importance!!! If you have the bathtub and shower next to each other that will be much better and then the glass separator idea should work. padmaramachandran's (see post above) setup sounds more reasonable to me as well (see first picture below). This is similar to your setup but as you have more space you could put in bath tub and shower where the picture only shows a bath tub. Also if you do it that way you could theoretically have a bidet or a wider wash basin (small double perhaps too). Example layout: Do you need a bathtub in the guest bath? If not you have a lot more room to work with. E.g. for a double wash basin and large walking shower and a bidet (2nd picture). Example of off-the-wall installation for toilet and bidet and a large walking shower. Finally if you ignore this advice and do it the way you planned ;) then I suggest you really thing about that glass separator. Doing it right will make a lot of difference (see 3rd picture). Good luck!

It small But your cabin sink unit is a good idea as you have storage space and it looks neat. I have changed my bath many times to shower unit and it has leaked every time, some times it has been the plumbers fault or bad design then it was a visitor who let the water spill while showering the last time it flooded the insurers wanted the bathroom TANKED! meaning waterproof walls and floors. This is done by an experienced plumber contractor of repute! as the insurers said too many claims from too many people with bad waterproofing. the insurer said they would not insure again or any other clients who had not got their bathroom water proofed by expert plumber fitters. SO I have gone back to the Bath with a shower enclosed and found it tops for waterproof.

Buying taps for three new bathroom sinks: 80cm, 70cm & 60cm. Any guidance on tap dimensions welcome.