OK, a final update.
Samsung were totally brilliant with their follow up service. After their technician reported back to them they insisted that he return, take the TV away and leave behind a loan TV while they carried out some tests.
Their technician updated the firmware and also changed a chip and had the TV back to me within 3 days.
IT STILL DID NOT CONNECT TO THE INTERNET
BUT
while he was in the house the technician relocated the TV up stairs to sit beside the airport express.
IT WORKED!!
So, Samsung Smart TV is seeing the airport express downstairs and registering a strength of 2 bars but it seems that this is not a strong enough reception for the Tv to connect to the internet. (Despite it being strong enough for the various laptops in the house at that location!)
I need to either update the airport express and get stronger reception downstairs or get a reception booster downstairs.
Overall, I have to say that i have been very very impressed by Samsung's approach to this problem and take my hat off to them.
Hope this helps