I worked in IT into my late 30's before going to school for some of the reasons you list. I got so much out of it. When you go back, you know which courses will directly help you, and you will probably learn many new things about where your strengths and weaknesses are. This is how your situation is different from many who enter college directly from high school who may not know what they want to do. Self learning on the job got me where I was, but the education got me further. Plus it really helped how I study and learn, so even the softer skills I learned prove beneficial today. Good Luck!
As a support manager, I was ready to tweet "Always Listen to your support manager" until I saw it was $4MM in revenue...
This is one of the reasons that is hard to adopt the "80/20, walk the difficult customer" approach; I have seen the right manager turn a bad client into a good one too many times. Live by the sword, die by the sword.
Yes, face to face is best. It sounds like they aren't oppressive, so this should be possible to do the right way. As someone who has both quit jobs and had staff quit on me with varying degrees of decorum, the way you handle it determines the long term result. You may be surprised at their response. If they have any experience, they will understand it is in their best interest to end things gracefully. It may not be comfortable the first few weeks, but time heals all wounds, and you may be able to use them as a reference or connection later on down the road.
PS if they throw more $ at you, don't bite. Chances are you will quit again within 6 months. Good luck!
That's good to hear you found your niche. I sometimes look back with pangs of regret, to be honest. When my compan(ies) needed visual basic help, I figured it out. Then never used it again. Then repeated that over and over with asp, php, sas, sysadmin, graphic design, crm, erp, even non-tech things such as accounting, loss prevention in varying degrees... So I can't really apply as an 'expert' at any. I don't dwell on it, but I am not sure if I would do it exactly the same way again.