Poor floor plan with sloping roof attic

You just placed the skylight in the bathroom area arbitrarily - right?

No. Exactly where I want it. It's usually cheaper if you only build the new one. The OP should specify which exact window is going there. Then it can also be drawn in.

The currently small roof window would be removed and replaced with one of the same size as on the other side.

Why don't you draw that in? It would then also be a bit higher than where the insulation is.

We were able to take over the sliding wardrobe from my mother. It was very expensive and we thought of using it as a room divider.

Is it standing in front of the window now? If only two of you use the bathroom upstairs, then open the whole space, use the wardrobe as a room divider as planned, partially separate the toilet, and position the washbasin and shower more into the room—so that it fits well and everything can be used conveniently.

It still has to be considered where the connection for the drain is located. That still has to fit.

Is screed actually being laid there? Or what is the floor structure like? Well, as I said, a better dimensioned plan with contour lines, etc. is needed.

Just draw it. It’s then also a bit higher there than where the insulation is.

Is it now in front of the window?
If only two of you use the bathroom up there, then open up the whole room, use the cabinet as a room divider as intended, somewhat separate the toilet and place the washbasin and shower more inside the room, so that it fits well and everything can be used comfortably.

The OP is quite sparse with dialogue.

At least the OP drew the cabinet there.

In my opinion, making it into one big room is not a good idea. The bathroom should be 22 degrees, the bedroom rather less.

Will the OP get back to us again?

Somehow my cut and some of the text have gone missing.

You have now placed the skylight in the bathroom area arbitrarily - right?

No. Rather where I would like to have it.

Removing the old one costs unnecessary money.

To the OP: what kind of window should go exactly where? 1m wide is possible with the replacement of a rafter.

But maybe it can also be done with the existing window in the gable? The closet can’t be placed in front of the window anyway. In the sleeping area there is the skylight.