Air lock question

[RJDubya]

So, yesterday a plastic pipe snapped off the top of the radiator and i lost a load of coolant. It was the pipe between the top corner of the rad and the header tank. I think ive fixed it (apoxy right round it until hard, complete botch!) but since i've never flushed the system i was wondering if this may cause an air lock and if so how is best to check/get rid of this? Currently have the car running and am checking the header intermittently which the level was going down in but seems to be constant now.