Don’t worry too much about form.
I used to swim laps with a friend whose mother was an almost-Olympic swimmer. He has an incredibly flat crawl and wonderful form. I would just get in the slow lane and swim away. We went almost daily to the Y for more than a year. One day, a substitute life guard that had not seen us stood at the end of the lane and as I touched the wall before my turn, he leaned down and said sympathetically, “It’s been a while since you’ve been swimming, huh?”
I didn’t care. My stamina improved, my speed improved, and swimming is a wonderful stress reducer for me. Hard on the hair, but otherwise great.
Sometimes hotels let locals “join.” They are open evenings, but not 24 hrs.