G'day Bad Bazza,
Not familiar with Allycore but we've just started distributing a product called 'Alupanel', it's essentially a 3 or 4mm thick panelling with a Polyethelene core with a thin layer of Aluminium (0.3m) over each side, the stuff is brilliant, it can be cut with a saw, drilled, routered by hand or on CNC machinery and even folded!!! I'm currently making a bait tank and a few other bits out of it by cutting the exploded shape out on a CNC then by routing down to 0.5mm you can actually fold the sides up and use some angle to fix the joins, ie, bait tank is made of one piece, not 5!!!!! I wish it was around when I fitted out my tinnie, it's a hell of a lot liter than marine ply and cheaper too I think. Only issue is it's high gloss finish would be very slippery, no worries if you're carpeting it or using it for panelling, comes in a range of colours too.
For more info check it out http://www.multipaneluk.com.au/ , drop me an email at work tomorrow at j.douglas@nover.com.au, I'm based on the Goldy but we have branches who have access to it along the whole East Coast of Aus, hope it helps, Cheers, Jamie.