Thanks for the info and advice, its given me a lot to think about.
I went out on the trampoline today to simulate double, triple and quadruple twists both left and right with fixed legs to see how it felt and the effects the larger body shape would have on my rotation, being a right twister in trampolining I though I may find going left a problem, but I can do both nearly, equally as well.
It felt really odd taking off and landing with feet wider than my shoulders and not being able to move my legs felt really weird especially when I was off balance.
I'm going to look at cheap boards as suggested, and I agree that any program would have to be linked to and in conjunction with actual snowboard training.
Please Santa, make it snow in the UK!