GQ Y60 Electrical / Starter Issue

Can anyone help me or point me in the right direction to help me find the problem in my GQ Patrol ??

Iv recently been tidying up and building a 1989 gq y60 wagon.
Prior to any of the work iv done it was running (but running rough) over and started every time.
Iv replaced all the filters, gaskets and oils. When I fitted the extractors and new gaskets with exhaust gasket sealant, I stated the Patrol to running temperature as directed so the sealant sets.
Now it did need a jump start as it was just winding over but it did start with a jump. While it was running. All dash lights and gauges etc we’re working.
Since then iv done a bit of maintenance and changed a few switches as they were faulty e.g
- electric Ariel switch - driving light switch - clock
Made sure they were in working order and did what there purpose is used for and they did.

Since fitting and putting the dash together and having charged the battery, when I go to turn the key it’s just a clicking sound. Like a relay clicking. It’s not even trying to turning over and none of the dash lights are coming on to glow the motor and the radio isn’t coming on.
Any help on where to start would be a grate help.

Your Cranker battery is knackered, or
Your Starter is knackered, or
You have a high resistance in your cranker circuit (the clicking you hear is the starter solenoid)

Clean the battery Terminals, check voltage for absolute min of 12.5 but 12.7 or higher is better)

Recharge the Cranker Battery and load test (if you don't have a load tester, turn on head lights, try to start, if lights go out battery is knackered, if lights stay reasonably bright Starter/Solenoid/Wiring is faulty)

Add an additional Earth from Engine to Batt -ve (even a jumper cable will do to eliminate bad earthing)

If all that doesn't get it going, remove Starter and Solenoid and overhaul (solenoid may be high resistance, starter commutator,/brushes /etc may be knackered)