JorgenCAB

Real life does not work in turns either... if you can see the enemy far away enough you could always intercept them. In the game you need to make sure you can see far enough out that they cant spend a turn passing your fleet. In this specific case you would need to keep the fleet a few hexes away from the station in the direction you anticipate an enemy to come from. This way they could not traverse your field of view in one turn and attack

I bought GC4:Supernova in the Epic store at a discount similar to a normal expansion pack for a regular game, no big deal. You should be able to get Supernova at a discount if you have GC4 in the Epic store, I'm sure of it.