Hello again, Grogy!
For one thing, you already have a job. Correct? You have a family that is supportive of what you want to do. Correct? You already know that the learning of these things will be a long process.
I admire someone who is committed to a goal as well as family and is willing to change in order to better themselves for the potential of making a better life for themselves and their family.
If you have had a stable job history, that is one thing that will work in your favor when you do learn the things that you need to learn and eventually apply for the type of job that you want. I would suggest making yourself indispensable at the job that you have now so that a reference for you will be more than favorable.
I would also suggest going online and finding some sites that are free for you to use that will help to better yourself in your grammar and spelling. What and how you communicate on cover letters will more than likely be the first impression that you will have on a potential employer. Using correct spelling and grammar will also enable you to do better at whatever job you have if you need to communicate in writing to anyone else.
Here are a couple of sites with subsequent links that might be good for you to use. Although they might seem to be pretty basic, I notice that you are misspelling as well as leaving out certain words with what you are trying to communicate by writing. Even if you think that what you have written is correct, always use the spellchecker.
Learning English vocabulary and grammar with free online English language tests, exercises and quizes
Grammar Style refdesk.com
Hey! You know what? You've already got one up on me, because I don't even know what a stationary engineer is or a power engineer is!
As far as learning math at your age, there is going to be some problem with retention on your part. You are going to have to study harder than someone who is much less your age. But, you can do it if you try. You will need to immerse yourself in your studies. There will need to be a little sacrifice as far as balancing family time with study time.
Just an idea - maybe there might be a retired math teacher in your area who would enjoy tutoring you for free? Again, just an idea. Also, maybe you can afford to hire a tutor?
You might find some online sites that will help you in your math to prepare you for the type of engineering that you want to go into.
You might also consider enrolling in some math courses at a junior or community college. The cost at one of those places wouldn't be as much as it would be at a college or university.
Please remember that it's not just practice that makes perfect, but perfect practice that makes perfect. In addition to immersing yourself in your studies and practicing under the guidance of a teacher and/or tutor, you will need to take periodic breaks from all of the brain work for it to "sink in" and then return to your studies refreshed and able to go on and learn more.
There are at least a few real math whizzes on this site. And, I am sure that any one of them would be willing to help you to figure out any math problems that you have and ways that might help you to understand the functions of the math that you are trying to learn concerning the applications that it might have to the type of engineering to which it applies.
I wish you well in your pursuit! And, I hope that there will be others who will provide their answers, opinions as well as insights about your inquiry here. I encourage you in the positive pursuits that you have for yourself.