Spat in back in!! Look at the pic from the manual above - 'the coolant is toxic' :eek
STiX, i did exactly the same as you, looked in level in the side window, no coolant. Opened up the expansion tank as per the manual tipped a load in, then realised i was brimming it!!!
Found a long peice of tube and sucked the stuff out, and being thrifty spat it back into the coolant bottle.