Hi Pondgirl  - thanks for your reply - we will go to Mayors when we're next down.
Hi Angela and John - what we are looking for are the metal posts (piquetes?) and then the galvanized fencing (not panels) - a bit like chicken wire but not in squares - more in lines if that makes sense - you see it all round fincas around Tortosa.  
We found a good guide on how to install the fencing on the Leroy Merlin site but no reference to them selling the posts or the wire fencing.
Thanks for your help
Haze and Alan