Hi Lancealot and welcome. Don't be scared of your new land.
For deciding what to keep on it, why not start at the other end? What would you want your animals for? Food, milk, eggs, fibre or pets? Do you have any experience of any species or breeds? How much time and money do you have available to buy, feed and care for your animals, including vet bills? Are you too squeamish to dispose of sick animals, or to take them to the abattoir? All of that needs to be discussed and agreed with your wife - there's no point diving in and buying unsuitable animals that one of you doesn't want.
Animals are not your only option, as you could have a flower meadow, wildlife area, or an orchard. You could grow garden flowers to sell, or set the ground aside for a Glamping business. There are endless possibilities, but there is absolutely no need to rush into a decision. Until you have made up your minds, you could sell the grass as hay.