You can get these from any motor factor for about a tenner for a whole set of 'em. Got mine from Partco if I remember correctly a few years back.
call me stupid but im sure ive seen a guide sumwhere and to undo the top strut nut all u need is an allen key and a ring spanner? or am i just talking poo?
once that top nut is off and youve remomved it from the car you need this tool to get the topmount off the strut. Last one I bought was a fiver or close from a local motor factors. Koni never gave me one with the struts I've got from them, I guess the re-seller was nicking them and flogging them on .....