Hi Tobynator,
I'm in NZ too, so know where you're coming from - we seem to have particularly complex shipping options here with urban & rural, different islands etc. I had to use the weight-based shipping module, as mentioned by Basara. Yours might be different and will depend on number and type of products but to give you an idea, I created two locations in System/Localization/Locations, one for rural, one for urban. Then in Extension/Shipping turn on the "default_weight" module. In there, under Additional Settings, you can specify the pricing for each of those locations based on the unit of weight you've got set for the cart (somewhere under System/Settings). I set mine to Kgs, so under Additional Settings, I have 1:5.00,2:7.50 for urban - this means 1kg is charged $5, 2kgs is $7.50. For Rural I used 1:8.00,2:12.00. Then you specify the weight of each product in Catalog/Products. It might work out OK for your products but in my case I had to "make up" weights so that multiples of the product would still fit into the pricing structure for the cost bracket in Additional Settings (mentioned above). If you have a lot of products, you might need to use Excel first to help get all the pricing & weight options sorted. Cheers, Rich.