Insurance For Free MA Class

Hi, I have a question relating to insurance.

I want to offer a free martial arts class, but if I do will I need insurance?

If the class is free then technically the people I will be training with will not be my clients, so I won't have a legal obligation greater than say playing a game of football with friends.

I've read that when people engage in such activities that they assume a certain amount of risk and that this can act as a legal protection to a certain degree.

So if you go to a boxing class and get punched in the face and try to sue then your case will not get through court because a certain amount of assumed risk i.e. the risk of being punched in the face, is assumed when taking part in the sport of boxing.

Should I get people to sign waivers regarding injury before they train with me even through I won't be charging?

I've heard different things about waivers, that they are a legal protection and also that they are useless.

I live in Queensland Australia so I guess the laws are different in different places, so if you know where I should be able to find this information I would much appreciate you pointing me in the right direction.

I'm not planning on having a store front. I'm thinking of meeting in a public place, maybe a park or my local university or youth centre.

The reason I'm asking is because I want to offer the class for free, but if I have to pay out of my own pocket for insurance then that wouldn't make sense.

Cheers