I had initially started making my mind map with Mindomo, thinking that it was completely opensource software (my mistake). I hit a wall discovering it was 'freemium' software - it's free within certain boundaries, and it prompts you to purchase a subscription if you want to create more than 40 nodes.
So, after a bit of searching, I found Freeplane - which is well and truly a completely free, opensource mind-mapping tool. It did require a bit more learning and you do have to do everything manually - all the way down to choosing the colours of your links (no templates here), but once you get the hang of it, it's a fantastic tool that allows you to have a lot of creative freedom (for something that costs you nothing, that is).
So, Mind Map update - it is still pretty incomplete, but as a tool, it definitely works for me.
And.....just as an update and to avoid allowing Mind Maps to take up valuable blog space, here's the final screenshot of my mind map. It ended up being A1 in size, and far too large to upload (though, I have tried).