I believe that the o ring seal that goes round the rode has gone. Transmission oil leaking onto the cluch plate causing it to slip. would need to replace this but really dont know how. Can someone help me, possibly give me diagram pictures.

Here is a link to a number of workshop manuals someone game me. http://www.golfgtiforum.co.uk/index.php?topic=54388.0

Have not had a look at it myself yet but imagine there should be something in there to help you. If not, you may want to invest in a manual.