Good for you. Swimming is fun. A couple of years ago, I learned to swim with a masters' group. As a beginner (and I still am), here's some things I found:
Even with being pretty fit from running, I had to rest at the wall almost every lap in the beginning. That gets better pretty quickly.
Learning to relax and breathe was harder than I thought.
Even though you are in water, you are sweating and can get dehydrated. So bring water or Gatorade, depending on how long you are swimming.
Our sessions were 90 minutes and I was very prone to leg and foot cramping. The Gatorade type drinks would help some, plus over time my muscles adapted.
I tried to forego the ugly swim caps, but I needed it to keep the hair out of my face. The spandex caps are more stretchy and comfy than the latex ones. The latex ones are so tight and they would give me a headache.
To protect your hair (which is gorgeous by the way), wet it with tap water before you get in the pool. It won't absorb as much chlorine. The swim cap does nothing to protect your hair. I naively thought my hair would be dry with the cap!
Eating before practice hurt my stomach. All those flip turns coupled with accidentally swallowing some pool water (yuck, huh?) = a nauseous tummy. Other people would eat a big dinner before practice and feel great. Everybody's different.
Swimming, especially in colder water, is notorious for making people extra hungry, myself included. Supposedly your body temp drops from the cold water and your body looks to the thermic effect of metabolizing food to warm up. At least, that's what my tri book says
and they suggested spending some extra time in a hot shower or drinking hot tea afterward to raise your core temp and blunt the hunger.
Swimming is like golf. Lots of technique.
Hope you love it!