I finally got round to working on this a bit more.
I screwed it all up to see if it fits together. Now I am planning on taking it apart, glueing it together, and make sure it all fits perfectly. Paint it with water proof undercoat, then final coat after that.
Here's some pictures of it where it'll be going
I still haven't decided on what lighting. I went to some lighting shops and Bunnings but most were pretty expensive. Probably looking at two 2' T5's but will continue looking for them somewhere cheaper.
I am also thinking about changing the gravel into something smaller and darker. I am also planning on repainting the inside of the box the tank is in to something darker.
And then have also got to source some plant for the tank, which is the whole purpose for the lighting etc.