Don't fertilize your potatoes with horse manure. It causes them to get scabby. We learned that the hard way. They are still good to eat, just really hard to clean, and don't keep as long.
Have fun gardening! I've gardened my whole life. My family puts up most of their food themselves. Garden, fruit trees, berry bushes, milk cows, beef/game meat, etc.
On the goat thing.... Goat milk is nice, but it is really easy for it to get bad tasting. You have to be careful as to what the goat eats, the milking area has to be extremely clean (no straw or manure around), and you have to cool the milk as fast as you can. Also you can not have a buck within smelling distance. So it can be just like cows milk, but it can turn nasty real quick. I want a goat as well, but I probably wouldn't keep the milk for drinking, I'd have a cow for that. The goat milk can go to making calves, kids (as in baby goats), pigs, chickens, cats, or dogs happy and healthy.
I grew up milking cows, and we also took care of a friend's goats off and on for about a year.
I can't wait until I am back on a farm and am able to have animals and a garden! I sure miss farm life!