got a 'battery low in key' message on my dash today on the L322, im assuming its a simple remove and replace? nothing else i need to do?

It should just be a simple battery swap, its easy to open the keyfob up with a small screwdriver or knife.

However - it might not actually have a low battery. I once had this message, then before I got around to getting a new battery the message went away. It first happened when it was a particuarly cold day. Cold is known to affect pretty much all batteries. So just as an experiement, before you go and change it, next time before you go to put your key in the ignition, just leave it in your pocket for a while and see if you still get the message. Might sound mad, but mine gave that message over 9 months ago and its never repeated it since!