WELL well well............. just as my patience was running out!!!! Its all been sorted!!
Yeah, not so sure about my mechanic and his DODGY auto elec friends diagnosis of "oh, its a common MK3 electrical problem!"
MY ASS!!!!!!!!!!!!!!!!!
This just looks so extremely messed up to me......... So, i was digging around behind the fuse box trying to check continuity and what not and was about to bypass the fuse box altogether as a LAST RESORT Suggestion by my Auto elec brother back in South Africa....... when i stumbled across this GREY\GREEN wire which runs from the back of the Demister switch and into the fuse/relay box, I noticed a strange wrapping of Grey insulation tape ( looked quite fresh

) just before the wire hit the box..... "someone" had connected another wire to this wire and then proceded to connect this to another point on the fuse box?

strange... i thought???!?!? Lets see what it does!
Wire out & WHAM!!!! Everything BACK TO NORMAL!!!!! no more problems with my headlights switching on my demister or vice versa!
Originally gave the car to the mechanic ( First time using this guy ) to fix up a ecu problem.... costed me £200. Someone here think that this A$$ was trying to make some extra bucks off me??? this problem didnt exist before the Ecu was "FIXED"?
Oh,,,,, and by the way....... FYI....... there is a relay for the demister..... its relay 16 in the Haynes Manual.... otherwise known as the "X" contact relief relay ( well , it stops the demister switch working so Im presuming this is the B1tch i was originally looking for

)