Buy a couple of king sized cotton bed sheets from the cheap shop and have them double stitched together. That covers the car nicely with a breathable cover at a good price!
No need to chock the wheels if on the flat, just leave it in gear or park if auto.
As said , do not start the car but do brim the tank. The amount of degredation to the fuel in minimal and it won't be nearly enough to prevent it starting in the springtime but it will keep any condensation away. My old lawn mower always starts
If for any reason the car is damp when it goes away , leave a fan heater or dehmidifier in the garage for a while with a draught excluded at the bottom of the door.
Then go in the house and don't worry about it for the entire winter.