Carolyn: the side of the vanity is almost against the end of the tub as in an L shape with the tub vertical and the vanity horizontal. The shower head is at the opposite end of from the vanity. Because the side of the vanity is right up to the tub, entrance to the tub is at the showerhead end. A glass panel there would eliminate an entrance into the tub. A glass slider may do, but I have glass doors in another bath and thought one glass panel would be easier to clean.

With a tight layout, sliding doors will be the best option. Get a high quality unit & have the glass glazed (sealed).

You could have glass all the way across the opening with a swing out door near the shower head end.

This was a real dilemma for our guest bath in terms of being able to turn on the water without getting sprayed with cold, and then getting in once the water has warmed up without flooding the floor. We decided on barn style sliding glass doors. A pain to keep clean, but works really well. Open and close on the right just enough to turn the water on, and climbing in from the left. Would you be able to slide the door enough on the vanity side to get by?

If the glass door opened outward at the shower end of the tub, one could reach in to turn on the tub spout to achieve hot water. Then when it's hot, you could climb in, close the door and turn on the shower.

Or you could just install a hot water recirculation pump to get near-instant hot water