I went to the one in Brisbane, Queensland last weekend.
I don't know how helpful it would be for "planning" a trip. We went with all details of our trip planned. All we were hoping to do was buy plane tickets and we knew what carrier we wanted to fly and all the preferred dates of our flights. It was absolute chaos and it still took us almost three hours just to get the pricing for the tickets, book them and pay for them. And this week we have been dealing with a number of resulting issues, including the tickets being booked in the wrong names!
We did save money booking the flights at the expo, but I couldn't imagine walking in there and trying to actually plan an entire overseas trip.
Disney did have a "booth". There was an Olaf statue dressed in Hawaiian clothing, two brochures (one for LA and one for Florida) and a bowl of DVDs. There were two "Disney" cast members there to answer general questions, but they weren't particularly knowledgeable. For example, I asked whether Walt's apartment would be included in the "Walk with Disney" (?) tour at LA in 2016 and they had no idea what I was asking about. They really just seemed to be there to convince people to stay in Disney hotels when visiting the parks.
I would recommend going to a
travel agent before the expo to help "plan" the trip for free. And then once they have provided you with a suggested itinerary, flight details, accommodation suggestions, etc head along to the expo and see what you can find. I would also recommend going there first thing in the morning before it becomes crowded and chaotic.