The headlight washers work only when the headlights are on, pull the washer stalk for about 3 seconds and whilst the winscreen pump is continously running you should hear the 2nd pump pulse twice - once for each lamp.
If there is no water at all on the headlights then suspect the h/l washer pump located in the washer bottle under the scuttle or blocked jets below the h/l, both are pretty common problems.
There are two seperate but identical washer pumps - one is for the front/rear glass and the other for the lamps, you should be able to get aftermarket pumps about £10 each.