If you have never done any motorsport then i would suggest trying the public skidpan events via MC Motorsport. They are relatively cheap and a good introduction.

As for applications, i've recently joined No Limits and from memory it was $15 annual membership to the car club, and then you have your event entry fee too. You will have to fill in an entry form to the car club, and also an entry form for the event. If you email Brett @ No Limits he will be able to clarify.

And afaik, your regular comprehensive insurance will not cover you at all on the track.

Good luck!