I have been working with a couple of swimmers using the Total Immersion Book as a guide. One has progressed really well - he could swim, but very little, and now does about 40 lengths at a time (not all at once yet, but he is really getting there). For him the book and DVD worked great.
My other friend has a fear of water and though she already swims well enough to benefit from refining her stroke, she cannot take the instruction because she does not like having her face in the water. She still can't swim a lap, not because she can't, but because she hasn't been able to address her fear. So the book would be useless to her until she can be more comfortable in the water.
I would suggest taking a beginner's class in swimming that focuses on water familiarity and getting used to the water as well as some instruction. You need to be comfortable in all positions in the water before Total Immersion will be of any use, but it's not hard to get to that point if you build a good foundation of basic skills. Once you do, I wholly reccommend the system. I'm a former competitive swimmer and I have learned from it myself, and my one friend who had no water fears, just poor swimming skills, has gone from barely making one length to doing many, as I said above (his ambition is to do a triathlon and swimming is holding him back).
Hope you can get involved with the water. It's very kind to your body and a lot of fun. Good luck.