Connecting a water butt to an irrigation system/ best water butt tap

Kashcroft57

I'm trying to set up an automated irrigation system for my pots, to be fed by a water butt and controlled by a timer. The idea being to keep garden pots alive while I'm away from home. I bought a Ward slimline water butt and Straight replacement tap, the packaging claims its is compatible with Hoselock products. The Hoselock tap connector does attach but once there is any pressure behind it i.e. an irrigation timer set in the off position, it leaks and i lose all my stored water.  Please could anyone advise how they have achieved either a water butt fed irrigation system, a water tight hose connection to their water butt or a water butt tap that is truly compatible.  Thank you !