Good for you for trying swimming!
I actually hated swimming as a child, even though I was actually pretty good. I hated being cold

So, after a 20+ absence from the pool, I decided to take aquafit to fill in the time while we were on strike. I soon got bored of that and took a swimming lesson. Then I joined a Masters club, and before I knew it, I LOVED swimming.
Fins are good if your ankles aren't flexible. And when kicking, remember to kick from the hip and not at the knees - you lose all your power if you kick from the knees.
I personally don't use fins because they bother my knees, and there's just something really deflating when you take them off and feel like you're going nowhere!