I am in NZ, so my situation may be a little different in ways to yours.
im on my 3rd year at uni now. I didint take my 2 horses with me to the city but i still have them. I was lucky enough to be able to leave them in the care of my wonderful mother. But on the other hand i do travel for about six or so hours on a bus every 2 months to go home and see/ ride them for about 2 weeks then travel back to the city again.
My 2 are older aswell, i have retired one horse now, hes 24, the other horse is about 19/20 and still ridden when i go home. Leasing wasnt the easyiest option for me as the type of horse Boo is so i descided not to go that way.
I miss them all the time......and buy the time 2 months is up im itching to go home and ride. I wish dearly i could take them, but its very expensive were i am , and the closest i could keep them to me would be about 1/2 hour to 1 hour away......and with no car ... well things would be difficult just getting to them.
I have heard stories of people taking there horses to college/ uni with them and altho things were full on it was the time they spent with there horses that was the time out for them, it was there way of relaxing while they were going through the stress of exams, study and such things.
but like you said your horse is a special needs so this may not be the case.
Either way.........good luck with your descision