I did my last semester external through UQ because DH is in the Army and we were relocated and tbh studying externally craps all over internal. You get sent all the lecture material and readings you need, you get marked easier, and they tend to pay more attention to any emails, enquiries, etc that you do have. Plus you can do the work on a schedule that suits you, and if you do live near the campus there's nothing stopping you from going to the classes anyway - and many uni's now have lectures recorded which you would also likely get online access to. I'm thinking about going back to do my Dip Ed because there's no way I can get a job up here in my field, and even if we didn't look like getting relocated again I'd still go with external just because of the flexibility and the resources handed to you on a platter!

Like Trillian said, it can be hard to stay motivated, especially with a really really boring assignment, but they often hook you up with a network of other students so you can contact them for help/support. You also have to really like reading. As a highly unmotivated person who absolutely abhors reading, if I can do it, you can too!

The only thing you might run into trouble with teaching is the prac requirements, so you would best to call/email the uni's you're considering to see what they require of external students when it comes to that.