I have to laugh a little about resumés: there's one camp that specializes in making people look like God's chief of staff, and then there's another camp that "dissembles" the resumés to try to decipher what the guy really knows!
But, a good honest report cannot be faulted, of course. If you can present a convincing argument for your mechanical abilities and inclinations, it would be of great help. If you have built stuff, taken things apart, reasssembled them again, this, to me, would be impressive experience, before you actually get to touch a cnc.
While you work on manual metalwork, keep a diary of what you have done. Your prospective boss will want to know your ratio of success/screwups
Not a literal number, but rather an indication of how much responsibility he can safely trust you with. We don't mind so much training newbies who know they don't know, and promptly ask for instruction, than to see someone blundering along without a clue. Be humble and teachable. Learn quickly, if that is possible. Don't forget what you learn from your mistakes, either. We (employers) don't like to have to teach the same things over again every couple of weeks
If you can successfully follow instructions to overhaul or build something (this could include woodworking), that would also be a personal asset for you.
You need to be comfortable with the simple trignometry and fractions. This means that your math marks should look good, and if necessary, upgrade those skills with appropriate courses.
There are some employers who would rather not hire an "old hand" because they may be "teach- resistant". So consider that this is an advantage for you, and that your employer knows that he can teach you to work the way he wants it done.
Keep your machines and work area relatively clean and neat. Messes happen, but clean up after. Put your tools away, take care of the measuring equipment, and report malfunctioning equipment. Work safely, not only for your own benefit, but with alertness for the safety of those in your workzone.