I was 35 years old when I prepared my GMAT. I finally got 720 on my second exam after a year hard work. My English is even worse than yours when I started, but I have to say, you will get payoff if you really work hard and are focused. Based upon my experiences, If I were you, I would start with working on T words, but only take less than two month. Then I would force myself to get feel of reading as much as I can within a hour, that would take at least three months. after that, I would do OG, read jijing, and do exercises. Then take the exam. Take GMAT first, it is harder than T, but after G, you will feel easy on T and can focus on listening and speaking. Good luck!