There's a whole world of shelf-stable milk products and milk alternatives. Keep one or two on hand for when you run out of fresh milk. Just be sure to rotate your stock, most last a few months.
Trader Joe's sells shelf-stable whipping cream for about $1.50. There's no weird chemicals, it's just milk and carrageenan (a thickener found in many creams) which has been Ultra High Temperature Pasteurized (UHT) and then sealed. Also useful for baking.
Horizon makes single serving UHT milk boxes, like juice boxes, which are shelf stable. At $1 each they're a total rip off, and I've only seen them in 1%, but it's better than nothing. I use them when camping because of the small portion size.
In fact, many of the national organic milk brands in the fridge are UHT. Horizon is one. You can buy a half-gallon of UHT milk and keep it for three months.
Any shelf-stable milk substitute will work. Almond milk, coconut milk, coconut cream, rice milk, etc... Go for the unsweetened varieties, you can always add sweetener.
Evaporated milk comes in cans, so does sweetened condensed milk, and they keep a long time. They're handy for baking.
Buy a box of Mini Moo's, those individual serving creamers you get in diners.
"Bulletproof Coffee" is adding butter and maybe coconut oil to coffee. The nutrition claims are likely a bunch of hooey, but it might cut some of the bitterness.
If you're adding cream to cut the bitterness, try making better coffee. Buy good beans and learn how to make pour over. You can buy fancy equipment, but with a good grinder you can do it on the cheap.