I've been riding for 6-7 years.
I've leased a few horses in the past, and I would keep it at the barn I ride at.
I know enough for small things like cuts, lameness, and care for basic things like that, like standing wraps, cold hosing, putting medicine on it.
I can tell when something isn't quite right.
If it were something I or my trainer couldn't take care of I would have the vet come out to look at it.
His grain hay water and turnout would get done by the people working in the barn.