Mine keeps in the fridge for 4-5 days. In plastic jugs with cling film over.
If you get cream rising, skim it off and fill a jam jar less just over 1/3 full. Shake the jam jar until it's like scrambled egg and 'cleans the glass'. (You'll know when you see it.) Strain to get butter and buttermilk
You can wash the butter in water if you want, or eat it quickly. Add salt to taste.
Easy cheesey - let the milk stand until it turns. Strain through muslin. Eat. The whey is great for pigs or any other livestock - but introduce slowly to let their digestive systems get used to it. A cheese farm local to us lets the cows have the whey, so since your girl is thin, this might be an option for her?
Easy cheesey freezes well. Can use for cooking when thawed.
Easy cheesey lemon squeezey cheesecake. Make biscuit base using ginger biscuits, or digestive biscuits and ginger, and butter, press into tin, chill. Make cheese as above. Add a bit of lemon juice, sugar to taste. Whip till it stiffens. Spread over chilled base. Chill. Eat.
Custard. Bread-and-butter pudding. Blancmange. Milk jelly. White sauce, cheese sauce, creamed leeks.
And yes, calves or pigs. Puppies, chickens, ... Or just take less and let her rest?