Ok, let's hit all the questions here:
Scam
It's a good thing weightloss isn't your aim. Swimming is a known appetite stimulant, and, swimmers have been shown to typically retain more fat than their running and cycling equivalents.
Three times a week would be ideal for number of times. Three times is also the recommended amount for 0 to 1650, which frankly, is the best option for beginners:
http://ruthkazez.com/swimming/ZeroTo1mile.html
Technique wise it says a lot, by the time you've completed that you'll solve most of the very early swimming technique issues. Other technique features go on line and look at YouTube. There's some great videos about Ian Thorpe's technique, and Bob Bowman does a great piece on front crawl breathing. Generally speaking, swim around your breathing, don't breathe around your swimming.
Etiquette. Based on your post about dangling feet, you read the loneswimmer guide. Donal's guide isn't bad, but a bit too strict. The one thing that matters. Surprisingly few pools have sensible lane etiquette guides. Use common sense, however there's a few things:
- Give a quick check of the speed the lanes are going at. Join the appropriate lane.
- Be wary of the people around you. Let people go past if they're going faster, hope they show you the same consideration. It's annoying when they don't...
- Follow the directional arrows on the swimming lanes.
Three times a week from absolutely nothing. Yes you will definitely see improvements.
Goggles. There's a Speedo store in both Covent Garden and Westfield Stratford. I'm sure there's some more, but given you're in Ealing, pop in. The easiest way to know if goggles fit. Take a pair, push them up against your eyes with no strap. If they stick for five or so seconds, you'll be golden. Just need to adjust accordingly when they're on.
Shorts. Get some Jammers. Go to Speedo, Arena, TYR. Any will do.
Jonny 69
Open water complicates breathing because it becomes more difficult because of waves and splashing. Sighting also adds complications. Presuming we're just talking about pool swimming, watch this:
kd