Lisa I get the feeling that you have not gone out and bought a horse before.
You've got one known quantity standing in front of you and it is free but you are thinking of going out and choosing from who knows how many horses, one that you think might suit you, as and when you have got it home and it is used to you. And you have paid for it.
We Brits have a saying "Never look a gift horse in the mouth" - now you can
Take that to mean anything you want.
If you can agree to give the freebie back if you don't get on, then it has to be a good deal.
But welcome to the Horse World - this won't be the first difficult decision you have to make.