Sorry forgot to update...
- car was knocking Thursday and Friday to and from work so I arrange for my local garage to take a look Saturday morning
- first thing Saturday I drive up to garage and car is making knocking noise on the way
- mechanic takes car out for test drive and says it made no noise for him
- I tell him I'm defiantly not hearing things so he puts car on the ramps and has a good check around all suspension bits, heat shields, exhaust and can find no problem what so ever
- I then drive car home and its not made a noise since!!
So I have no idea what was causing the noise, but ill look at the cover plate for the discs if it returns...