When the radiator cap is off rather than feel the hoses give them all a squeeze.
Leave the engine running until the engine cooling fan comes on then put the radiator cap back on.
If the heater still won't work, let it cool and try again. Failing that you could be looking at a blockage.
Another thing to try, perhaps not in your case but to anyone else with heater problems is make sure the thing on the side of the heater moves all the way round when you set the control to hot. I'm pretty sure its behind the trim panel on the end of the centre console next to the clutch pedal.