Question

My battery is not charging and there seems to be no power to the lights or anything when I tried using an electric hook up for the first time with this van. How could I check the fuse or if its the psu thats faulty?

Answer

You need to check the output of the battery charger. Disconnect the battery terminals and check the voltage across the two wires with the battery charger switched on. This should be at least 13 volts. If not then you will need to change the charger
Is the battery OK?