Hey @Jen - two bits:
Insurance: We carry $20 million public liability on the farm, which covers most stuff from the insurance side, though for gatherings over a couple hundred we have to have separate event insurance, which we covered for the Joel @ Jonai event with the AFSA Community insurance policy (good up to 1000 people if I remember correctly).
Council requirements: this is unusual in our case, because our council is convinced that everything we do is under PrimeSafe, and we have not disillusioned them of this misunderstanding. However, for the Joel event we wanted to be sure we'd ticked all the boxes, so I contacted council and explained the event and asked for guidance. They had me fill out a 'Place of Public Entertainment' form, which exempted us from the main requirements of large events - we were a NFP & the event was under 5000 (!) people, so they didn't need a risk plan, fire plan, or anything! I had demonstrated in the original enquiry that we had a parking plan and sufficient toilets and they were happy. I hope this helps?