Well, my brief perusal of the Parks & Rec site had 3 levels of Adult classes that I could see - 1, 2, and, confusingly, 3. 1 was like "oh help I'm afraid of the water but I'm willing to learn". 3 was like "crazy mad racing swimmer person class". 2 would probably work for all of us. It just said you needed to be comfortable swimming for 15 metres on your back or your front - didn't even name strokes, so there should be enough review for you to pick up what you'd need.

Every year I say I'm going to take swimming... maybe this year I'll actually do it!