Its fraud to use someone elses card even if its your hubbys and got permission (not to say thousands do it)
But in oz you have to sign for it (unless getting money out of an atm) so you wouldn't be able to use it (unless you can also forge his signature

u )
You can be an additional card holder on his account, he just has to ring creditcards to add you.
Or you can apply for one on your own. The benefit of that is if one of you lose your card at least you would have another as joint/additional cards if one is lost the whole account is stopped so your card would be useless....