Car Cover and waxoil

[casbar]

Just bought my son a mini mayfair, its going to need to sit outside through the winter, and not get used much, whilst he learns to drive.

Is a cover a good idea, if so, is it worth paying for a decent one, such as cover craft?

Another question, the underside isn't waxoiled, I presume this is a good idea, but I presume the car needs to be clean and dry underneath before application. Are there companies that specialise in waxoiling cars, asked my local body shop, and they didn't want to know.