Not easy. There are cargo ships which go in that direction but you would have to approach individaul companies and they are not always able to accommodate children. The only cruise ship I know of visiting there is the Fred. Olsen "Black Watch" on her 2009 world cruise but this is going via Panama. She leaves Southampton on 06 January and only reaches Fremantle on 4th March - a very long trip. Perhaps someone can advise on cargo ships?