Replacing tappets

My engine has been making a tapping/knocking noise for a while now, considered going for a KR swap but ive decided to have a go at replacing my tappets to see if thats whats at fault. Wondering if anyone can tell me:

1. What parts do i actually have to replace
2. Where is the best place to get them
3. What tools do i need for doing the job

Thanks in advance for any help given

Have a butches here - http://www.vwgolfmk1.org.uk/modules.php?name=Forums&file=viewtopic&t=59579

its all covered   the only hard thing maybe getting hold of the 2 shim tools, but its not too bad, and worse comes to the worse you can also do it via cam removal.