Not really any limits to how many dogs you can own, but if animal wellfare thinks the dogs are suffering (for what ever reason) they can take them off you. And if you choose to adopt another dog over here in the UK, they do a home visit before you can take him/her home (I don't know if they do this in australia) and they could say no if you have a small garden, house 1 or more dogs(I know someone who had this happen to them).

You will be lucky to find a landlord willing to let you own a dog though, good luck with that, seriously. :P

Loads of people have pets over here, we're a animal loving nation (loads of people treat their pets better than other people). As said, there are loads of parks in the UK and loads of countryside. So you shouldn't have to much trouble with them having room to play.

Good luck if you choose to move!