You can preview the cabin in the
following TR BY Airxliban From Lebanon, which details the spa & showers quite well .. (scroll down if only interested in the same)
Click ME
After just having another brilliant set of F trips on EK (with showers both ways) I'm sure you'll enjoy your experience
Be sure to let them know of your preference as early as you can ... on my out-going trip it was a light load and I was able to have 2 showers ^ so it's all relative to the load & the FAs discretion in the end
Cheers,