Take both pipes off the engine and flush through both ways with a hosepipe. Make sure the valve is not blocked with crud. If you don't get some heat after that, check your engine is getting warm enough. If not try a new thermostat.
Don't block the hoses! It's not designed to take ~ 40 psi mains water pressure......Just flow the water through the matrix in both directions. And check water comes out of the heater valve when you open it. BTW - best to NEVER close it anyway!
THANKS FOR YOUR TIP'S, I'L LET YOU KNOW HOW I GET ON MY MY MY NEW PARTS ARRIVE. OH AND ALSO IV BEEN TOLD WITH THE OLDER CARS ITS BEST TO GET A CERTAIN SUMMER COOLANT , IS THIS RIGHT ???