Good luck in the program, one thing you have to consider is the effect of the job on your body. I think Chem Tech is the best of the 4 areas for older folks, those 4 being Ops, Chem, RP, or Maint. You don't want to be a new HP tech with physical limitations. I think that would just breed animosity. Swinging a meter and swiping stuff isn't in itself hard, but there still can be lots of bending, wearing protective suits, and other stuff that can grind someone down over the years if they are not prepared for it.
I think OPs is the most strenuous, lots of climbing, bending, twisting, walking, fire brigade, etc.
Chem Techs basically analyze samples in a lab, perhaps go out to turn a valve to get a sample, but for the most part wait for machines to spit out a data report.
Every plant is different, but at my plant, Operators do rounds, pull breakers, climb on stuff for vibes, do a whole lot of tasks that seem the domain of other departments, so you have to be fit enough to be a jack of all trades.
Also, I think there would be more longevity for an older person in Chemistry and opportunity to advance upwards within a shorter time frame than starting at the bottom of the NLO ranks and working upwards towards supervision. Unless you want to be at the tech level until retirement.
YMMV.
Whatever you all decide, I wish you the best of luck and welcome to the industry!!