A few thoughts....
Flights: there are plenty of companies that will fly from Perth to Europe. Try
http://www.bestflights.com.au or other comparison websites for current deals. Depending on where you are starting your walk from then your point of entry to Europe is likely to be either Heathrow, Amsterdam or Paris (possibly others depending on the airline). All will allow for intra-European connections to places like Madrid, Pamplona, Bayonne/Bairitz via air. You can take connecting trains and buses easily within Spain to your start point. If you are starting in St Jean in France then you may consider flying into Paris, train to Bayonne, Bus/Train to St Jean. There are plenty of posts on this forum that discuss the best ways to get to your start point.
Footwear: This should be your first priority now given the time. I assume you live in Perth or could get there. Go to Paddy Palin, Mountain Designs or the equivalent. The brand matters less than how they fit. Find a sales person who knows what they are talking about and can help find footwear that suits (read fits) you. By the best fitting footware you can afford. Consider both walking shoes and boots. With boots consider breathable fabric with gortex waterproof lining if your budget extends that far. Then buy then as soon a possible and break both the boots and your feet in. If you don't do this then the risk of blisters and a painful Camino increases.
Next work out what you are going to do for socks. I prefer a two pair system (eg coolmax or poly propylene inner sock and a different material outer sock). This is for blister prevention. Read the various posts here on blisters. In short there is no one method that will suit everyone but get to know what works for you and prepare. check out
http://www.rei.com for various sock options. If you order soon they should arrive before you go.
Clothing you should be able to get from the same location as your shoes, or also from REI. Train with everything you are going to wear before you leave. You don't want to discover that certain shirts, trousers, underwear etc rubs you raw when you are 5 days into your Camino.
I strongly recommend you consider hiking poles. In my opinion forget a single walking staff and get two (one for each hand) walking poles. Pacer poles have been popular on this forum (just search for them on Google) and they may still be able to send them from the UK to you before you go so you can practice with them. If not then buy normal hiking poles from Paddy Palin etc.
In September you may experience a range of temperatures. Make sure that your clothes allow you to have protection from the sun when it is hot, are breathable and yet are light and cool. Get a wide brim hat. Make sure that you have layers you can put on if it gets cold, windy, wet or all three.
A sleeping bag is required if you are going to stay in Albergue/Refugio accommodation. If you are planning to stay in pre-booked accommodation (eg Hotels / Pensions) with private rooms and beds with linen then it won't be required.
If you do not have your pack yet then get that as soon as possible and train with weight in it.
Approach: you have a few of options:
1. Do it solo with nothing planned or booked ahead.
2. Do it solo but book accommodation ahead etc.
3. Go as part of an organised group.
You will get lots of varying opinions on what you should do however no approach is more legitimate than another. My preference is option 2. I get my accommodation booked in advance, packs transferred for me and my wife each day. I only carry a light daypack. It costs more but if I'm going to spend megabucks to get to Europe I'm going to enjoy it as much as possible. I'm happy to put you on contact with the people that I use to organise this for me. Check your private messages.
Have a great time on the Camino.
Jason
