I've tried again setting up from scratch, both auto & manual and still no joy. Get the usual 5 channels fine but no Freeview.
Searching through previous threads here I did come across two others with exactly the same problem with LG TVs - 1 person was taking their TV back and the other got the same response from other posters, i.e. you should be able to auto tune, but both the threads died at that point so I don't know the outcome. A similar query on Fixya but no response there.
Well - I've just spoken to LG technical support and the guy I spoke to was really good. It just needed the aerial plugging direct into the TV, putting back to factory settings, then auto tuning and then replacing the aerial into the back of the DVD recorder. And everything is fine!
Thanks for trying to help.