i personally would take the aux belt of and start the engine, leave it to get warm and once you are able to move the water pump by hand re fit the aux belt and run again till fully defrosted, switch off allow to cool then dump the water and replace with antifreeze.
focus will bleed itself if you hold revs at 1500ish with rad cap off a knackered w/pump will show up by either noise or cold spots on certain pipes/parts of the rad/ parts of the engine if not pumping