This makes absolutely no sense. I have no clue what you are trying to accomplish. If you hadn't already said the planet is larger than Earth, I'd assume you meant they need to be the same size but as it is, I have no clue.
Intoxication and silly 5am ideas make for incoherence, sorry :-) I'll try better with good sleep and a slight hangover xD

So, thank you ever so much for the replies, guys/gals and I apologise for my complete incompetence with maths. Seriously, that subject is like carbs to an endomorph for me.

So, if I'm not mistaken. If I consider the entirety of the map, including sea + land, 1cm will approximately equal to 1354km?

It seems to me that feanaaro feels that I'm working with a sphere? I know I said 'planet' but if it makes things easier, the map I'm drawing works like a typical 'map' of the globe. Unless that's completely irrelevant.

If that doesn't make things easier, maybe splitting the globe into sections and working at them individually will help? For example:

The world at its current age is akin to Earth's pangea: it's one super continent. I considered the future and made outlines to what will eventually become 8 separate land masses. The largest being 30million kilometres square (around the size of Africa) and the smallest 10million kilometres square.

Again, I apologise for the inconvenience, but I still haven't grasped it fully yet. Since 1cm = 1345km on a global scale, how can I equate 30million kilometres square on a continental map?