+1 on Total Immersion
Also, I'd have to disagree -- on the basis of my own experience -- with anyone giving up on bilateral breathing because they find the oxygen debt too onerous. I taught myself how to swim with Terry Laughlin's books and one class over about 18 months, and I breathed bilaterally every workout, at least 90% of the time. My "good" steady-state 100m pace was around 2:00 and I left it there, working on almost nothing but technique and perfecting my bilateral breathing.
Then one day the week before a race I jumped in the water and did a 1000m time trial. I finished in 16:50, in a 25 m pool! That's 1:41/100m!
I continue to breathe bilaterally in 90% of my pool work. I believe being hypoxic all the time vastly increases my oxygen usage efficiency. I save breathing on one-side only for intensity work (which I rarely do), and races.