Get the course -- do some open water
If you are going to a place that caters to divers -- you'll want to take advantage of it, not spend the whole time training. As well, learning to dive in "cold water" will make the warm water seem really easy and enjoyable.
When both the wife and me got our cert. we were really going through the air at first. A 80 cu.ft. tank would only last about 35 minutes. After about 10 dives, I can do 1:20 on a tank and still have some left over. If you get trained down there, your doves will be short, and not all that deep. If you get some dives under your belt and then go, you will be able to push the Dive/depth limits rather than always running out of air.
You also get much more used to the equipment and more comfortable under the water, so you'll spend more time looking at the pretty stuff and less watching your gages and fiddling with gear.
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