Hi all,
I thought i should finish this post now the problem has been found. It looks like it was indeed the inner gearbox boot allowing gases into the cabin and only occurring when hot. This boot has a cable tie around it to hold it onto the gearbox casting and slips over the gearshifter, the cable tie was loose and on closer inspection there was a tear in the actual boot allowing them to escape. The outer boot (car body to gearshifter) doesnt seal that well so must have been letting gases up through it too.
On another note, i have been hassling local nissan dealer about my other issue of oil leaking from the throttle body. Initially I was told this is normal but it has got worse and dripping on the ground after a long haul so i pushed them again and they found leaking turbo and the whole turbo needs to be replaced.
This explains why the vehicle has been using about a litre of oil between changes and why everthing it gummed up, running oil injection of sorts

The scary thing is it has only been picked up becasue it was leaking, if it wasnt leaking i wouldnt have known until it failed totally most likely out of warranty. Nissan are going to replace the whole turbo as i got extended warranty (lucky).
I would suggest if your warranty is soon to expire and you are mechanically able to pull the intercooler hose off the throttle body and make sure there is not excessive amounts of oil in there, there should be a light film from the rockect cover recirc but not masses of droplets or pooling like mine was.
Thanks everyone for their help and suggestions