This is quite straight-forward once you have a Heavy tank. The earliest Heavy tanks are the French and German Tier 4 Heavies. Otherwise, you'll have to get to Tier 5 for most heavy tanks. Heavy tanks have a diamond with two lines through it by their Tier number.
Just start a game with your heavy tank, if you get destroyed you can just go straight to your garage and pick another ready heavy tank and play another match! It will take some time to get these two followup achievements but don't spend too much time watching games finish after you're out and it should go faster: