I think that you can do a wonderful thing, adopting a horse and caring properly for him.
That said, what will you expect this horse to do? If you want to open your window and see a nice pasture pet grazing happily, then almost any horse will do, though you might want to know about health issues and if the horse needs expensive meds or something like that (if you will keep the horse on your property, consider getting 2)
If you want a nice, well behaved, sound, well broke horse who can put up with young or teen grandchildren, that's another thing entirely, and you might not find any who is free for adoption, as a good and sound beginner/child safe horse does cost money.
You say you are disabled, I don't want to pry but to me it sounds like you won't be able to lift and carry the hay bales. Who will do that?
Even the healthiest of horses needs some basic handling, are you well enough to pick hooves, put halters on, check for ticks (that means between the rear legs usually) and so on? Again if not, do you have someone in your family who can do it? Do you have someone who can do it- and is knowledgeable enough to not create a brat of a horse who'll never even let you put an halter on? Even a pasture pet needs care, and it's not the vet's or the farrier's job to teach your horse to behave in a civil way.
And remember that many neglected horses might have been abused and they may be skittish or terrified or.. you get the idea. Yeah, a very good trainer can help you and the horse, but a very good trainer is a cost that you need to consider. And bear in mind that if you find instead a very bad trainer, you could lose money and end up with a more abused, more terrified horse.
Depending on what you want from the horse, the kind of money that you want to invest, the amount of help you know you will have, your options will be very different.