I went back to college in my mid 30's too (circa 95). Being an Instrument / electrical engineer i found technology had moved from pneumatics to electronics and programmed systems. I wanted to bring myself back up to date. I was the oldest in the classes but that did seem to give me a bit of respect from the younger guys and the lecturers. I also found college and studying a lot easier at that age than when i was 16-20 and more interested in bands, bikes and shall we say socialising.
Have to say it opened some doors for me within the Industrial Gases company i worked for.
I really enjoyed my 2 yrs back at college and came out with great results.
I would highly recommend being a mature student at college.
Dave