Booking Tours/Accomidation/Flights IN Vanuatu, or before?

Would it be advantageous for me to book my Vanuatu inter-island flights/tours before I leave (as in a couple months before) or would I be alright doing it after I arrive? Do the fees differ at all?

I plan to go in mid-september and am I bit concerned about the Aussie school break and Cruise season causing a lot of places/tours to fill up. Lonely Planet mentions that you should "Book well ahead" if you go in Sept.

Has anyone been there at that time? How busy was it?

Sorry for yet another question...

Thanks
JT

We were there last Sept and pre booked our Tanna trip with Melanesian Tours(highly recommended). We were very glad we did this as when we arrived we found that Air Vanuatu had canceled our reservation and the flight was now fully booked, as were the next several flights. Without the help of Glenda we would have missed out on getting to Tanna - I don't know who was bumped but we were given back our original reservations. You should prebook if you want to be sure of getting what you want. I would also recommend paying in advance to secure the reservations(that was our mistake). We did get a discount when we paid by showing our international ticket - I don't know if you can get this discount by booking over the internet or through a TA but be sure to ask. Going to Tanna was worth all the trouble.