Hi! If you're going away next year for a few months, why not wait until you get back from Australia? That way, your cat won't have to go through any unneccesary stresses and you won't have to worry about it getting along with the dog? Also, this will give you some time to save up, so you should be able to afford the kitty better. I'm not sure if anyone will be able to give you a total of the weekly/monthly costs of keeping a kitty, as it varies vastly, especially when it comes to vet bills: worming, fleaing, vaccinations, and any illness that crops up. By the way, are you planning to keep the cat indoors or let it outdoors? An indoor cat will need lots of toys and scratching posts to keep it stimulated, so that could become costly, too.

I get all my cat food and litter from Zooplus, as it's very cheap, and you can get some real good quality stuff. You could also get chep cat trees and toys from there, too! Getting a good pet insurance might be advisable as well, so that you don't get lumbered with any huge vet bills, especially for the first year until you get an idea as to how often your chosen kitty tends to get ill (I've got insurance with More Than, which is about £8 per month for a pedigree).