After much research, repeated trips to Chans Brothers and a trip to the airline ticketing offices, we've finally booked our air tickets from Chans Brothers. Their price is slightly higher than if we booked online, but as we have no credit card, we don't have much of a choice. Anyway, they'll handle the visa for us too at a fraction of the cost.
We'll now have to do lots of planning and research, to find the best deals and decide what to see. Not much time left.