Since you have light from a window that you want to illuminate the tub area, using glass as the "third wall" makes perfect sense.

I'm not sure what a "shower screen" is.

This is a shower screen

I had a "shower screen" in a former house which, to my surprise, was quite effective at keeping the water from the shower where it belonged. However, that was probably due in large part to the location/angle of the shower head. The shower head was a medium size rain head that, while not pointed directly at the tub bottom, was more downward in orientation than angled outward towards the back of the tub. The tile on the back wall (the shower was recessed into an alcove) rarely got wet, but I was glad that the wall was there.

Thanks, millworkman. I would have just called that a "glass panel". :)

Fixed Glass Panel is about right Jewel. They are very popular in Europe and that is what they are called there so......

They're called shower screens and I'm trying to figure out if that's what I want, too. Seems like most people I've read are happy with theirs so I think I'll probably go for it. A rain shower type water source is a must, though.