Create a landing page as the front I have created a content type called 'landing', however when I try and setup this as my homepage 

config/system/site-information to the alias 'landing'

It takes on the node--front.tpl.php as the template rather than my node--landing.tpl.php.

If I look at it in /landing the page looks fine.

I also try and hijack the main landing page by setting this in the .htaccess

DirectoryIndex landing

but no luck - any idea how I can set this custom landing pages as my homepage and retain the template style?
node--front.tpl.php is for the front page specifically.

If you don't want a specific template file to apply to the front page only, simply delete node--front.tpl.php and flush the caches. node--landing.tpl.php will then be used instead.