Newbie swim question

I have just decided to attempt my first sprint triathlon a. I come from a cycling approximately 100 miles per week. I am 40 years old, 6'1" 217 lbs (about 30 lbs overweight, but down from 240 lbs earlier this year). I am having a very difficult time with establishing a rythmic swim. My breathing is causing me the most problems.
I can't quite get the proper stroke techniques to ensure adequate oxygen intake to sustain a swim of any length. Each time I need to take breath I loose my technique. I was able to complete 200 yds in 5:35 this evening. This was my third time in the pool and I have gotten much more comfortable after trying to be more efficient but the lack of oxygen and proper breathing technique is hindering my progress.
My question is should I seek a professional to help me with proper technique or is there a book that I can read to help me? Any assistance is greatly appreciated!