swim teacher here so any questions shoot away
Couple of pointers firstly.
1:Enjoy swimming, sounds silly but if you treat swimming as a "exercise" and something that has to be done, then youll soon tire of it and swim less and less.
2: when you first start swimming you need to try aim for 3 session a week, learning as a adult takes a lot longer than when you were a kid as you've picked up bad habits or may have lost confidence. (getting into lessons a great way to start, then a fitness session/pool time session combined with either a routine given to you or a few good drills added to your normal session )
3: technique technique technique technique
Simple way to start out is by going through your BLABT order, body,legs,arms,breathing,timing.
If your body position bad will have knock on affect on everything else, same goes for legs as a wide leg kick will pull you out of alignment ect.
Ps dont ask Lgs for advice lol, thats a sure way to get them sacked (lot of centres now cracking down on lg and members of public talking to each other due to recent health and safety incidents )