Update. Job done
And what a difference. Warm air thro the vents within a minute. After looking it became apparent that you need to cut the dash(behind the glovebox) to get the heater out. on LHD its a piece of cake but RHD is different. As it turned out I didnt actually do the job myself but a friend although i did watch. Anyway basically as per the procedure listed earlier in the post by SI-R32. My aux heater did not have the dry joints so bought a second hand one on ebay. It was installed and then checked with VCDS fault code gone. Sweet!