Trying to go to vocational school while working full time.

Hey guys. I make really good money working in retail, but I’ve done it for 15 years and I’m getting really sick of it. Found a vocational school for electricians that fits my budget, and it’s schedule seems very reasonable. I’ve been raised in construction and know a thing or two about the ins and outs of it, including electrical work. I asked my GM if he’d accommodate my schedule (Monday through Thursday, two of those days off and the other two I can work 2-9, then Friday through Sunday fully open... plenty of room to stay at 40 hours). He shut me out saying that he probably can’t work with that. I have a real opportunity, but I need to keep this job in order to pay for school, so I can’t afford a switch. Is it unfair for me to be upset at my employer who, frankly, way over pays me, because he’s not willing to give me the opportunity to better myself while still contributing full time hours? Is there another direction I should go in? I feel very much between a rock and a hard place right now. I’m a model employee. I don’t call in, I far exceed sales and service expectations, but I want more for myself than working in retail. I just can’t afford one without the other, ya know?