I have a a4 3ltr pertol 2004 (asn) engine with a slight water loss and white smoke on start up but the smoke clears carried out a gas sniff test on the coolant system which indicated a head gasket leak would a clyinder head retorque help this problem?

 

I think that will indicate a blown head gasket. Did you try a compression test on each cylinder?
Just re-torque would not help at all. You must find the root problem, not to try to avoid it. You can get engine damage if not act in time.