Re: So I'm going to learn to swim...
Hi 4boysmom,
I unfortunately know nothing about the specifics of tri swimming, but I do have a few possibly helpful comments about learning to swim in general and knowing where you're going while swimming. (I'm used to swimming for time, not endurance, so hopefully someone can come in and ex-nay anything I say that just wouldn't work in tri-distance swimming.)
You can stay afloat and side-stroke. That's a good start. At least you are able to swim in some fashion. But at the very least, I'd recommend learning to swim other strokes in a pool, for several reasons:
One of the easiest ways to practise breathing is while NOT moving. You can stand in shallow water and bend over to do this (not terribly comfortable), have someone hold your feet, or you can get to a pool, where if the pool is relatively empty, you can hook your feet around the ladder or over the ledge and "swim" without going anywhere. This sounds stupid, but it really works. I recommend this because it is a good way to learn to pace your breathing, starting with very slow strokes, and also to side-sight on your breaths. Seeing your surroundings on the right and left is often as good as looking ahead. You will have a major 30 degree blind-spot right in front of you, which may be a problem with so many other swimmers in the water, but then I guess you can also practise sighting in this way.
The other advantage to not-going-anywhere is that you can practise the strokes you are learning very, very slowly. You don't need to worry about staying afloat or propelling yourself, just concentrate on what your arms are doing, and your breathing in time with that action, until it feels right. If you have very little experience swimming with your face submerged most of the time, it can be a little scary and you'll think of nothing but your next breath. Being essentially immobilized at your feet makes for a controlled environment. You can stop and breathe at any time.
Another option is to invest in a flutter board (very cheap), and place it under your chest. It will keep you unnaturally high in the water, but again you can learn breathing and strokes at your own pace, without worrying about either being necessary to your comfort and safety.
Best for last: Adult swimming lessons through your municipal community centre. They should not be very expensive. Less than $70 for 10 lessons over 10 weeks where I live. Private lessons are twice that, but either are a good investment. You'll enjoy swimming more if you have more versatility/skill in the sport.