Something others haven't mentioned might help along the way: see if you can get an office-type job at a construction company while you are self-learning and/or going to school. It could even be volunteering where you currently work to help out with any IT stuff.

You already know a lot more about construction than others like processes, procedures, etc. and in an office setting you will likely run into IT related work that needs to get done. It may not be building websites but it might lead to that ... lots of web applications are just a few steps beyond someone's Excel/Access contraption.