Pop down the coast here to Torquay, and I will paddle out with you and give you some tips...
You need to get a Longboard first though!

Size, yeah the girls boards would actually suit your weight.
This could be a well priced board... The 9'0 version.
http://www.ecsboards.com.au/comp-mal1SurfAnimal / SupAnimal on here speaks highly of them. Good value for money. Fast delivery too... Professionally Bubble Wrapped, and Boxed, and Professionally Delivered to your door, express freight.
McTavish also professionally build, and deliver boards to your door!

But cost more!