Hi yes the beer had finished fermentation.
The keg I referred to was a plastic one witch has a valve ontop like the one in the photo sorry for any confusion
I was told it was ok to prime with sugar and told to use 120g for 23L coopers lager.
I bottled 10 pints and left the rest so I would be able to pull a pint off the barrel when ever I needed to.
I was told that I would need to use co2 when the barrel ran out of pressure so as to keep the beer from getting infected and keep the beer fresh.
Just hope I've been given the right advice