Before you start studying for the new MCAT, you should first focus on figuring out why you were scoring sub-30 on the MCAT. For example, was it due to a lack of knowledge or do you simply have poor test taking strategies/skills?
You can do well with or without a class. Just depends on you - if you need structure then I think a class would be good to take. With your question about books, I recommend you focus on a single set from a prep company (ie. I am using EK) and then supplementing it with other prep companies/textbooks if need be (ie. TBR/TPR).