Vauxhall Corsa no heat from heater

I have recently had a new head gasket,done over 800mls since.Car runs great,temp.guage showing ok.No heat from heater,just blows cold.Checked the dash switch heater control cable,it is working the lever on the matrix.Tried bleeding the system from the inlet manifold temp.sender,to no avail.The stat is ok,hot water passes thro'the rad after a short warm up.The nearside heater hose gets warm,but the offside doesnt,I have had the pipe off where it joins the inlet manifold and there is water getting thro'.My Haynes manual only covers re-filling,but not bleeding out air locks,could you tell me how its done please.The hose from the heater is close to the multi injection system,and I am a bit worried about getting water in it.