Thanks for the reply!
I didn't notice the 'Change Maps' button previously...clicked it a few times and it cycled through small, medium large etc. so thanks for that, I've now found the custom maps screen.
I have just started a random small map and set the AI to Easy Fortifier...lets see if I can finally win a game.
Wish me luck!!
If you are playing diplomacy, make sure to turn the pirates off! Even if you're not, you might want to do that anyways, as they are a pain more often than not. Also if you are the kind of player that learns best by playing the game, but are having trouble staying alive, you can either play a map with no enemy AI players or with locked teams and an ally with you to help take some of the pressure off you.
Also, to make truly custom maps, you should download the GalaxyForge tool from the downloads section on this site. If you turn random positions off, you can make a map that really favors you (player0), by giving you lots of nearby asteroids, starting with multiple planets, extra ships, etc. You can also give yourself a ridiculous amount of extra resources, which can be nice for learning (as long as it is just for one map, a lot of the strategy in this game is how to invest with limited resources).