Beaches are (mostly) owned and controlled by Councils.
If you want to conduct a business on the beach (yes, you are),
any kind of business (such as selling food - yes, you are),
then you will need an approval (licence, permit, something) from Council, yes.
This will involve a fee for some sort of licence,
a condition of which may be having your own (public liability and other) insurance,
and full food safety compliance, if you are selling it as food (which in Council-think, you would be).