OK, time for an update as I just got the car back today.
The workshop who did the work are old school and know what they are doing and do not charge extortionate hourly rates.
They ordered the rad on Monday afternoon and when it came on Tuesday it wasn't quite the same one, it had no pipe coming out of the top of the rad on the passenger side, apparently this goes to an expansion tank.
This was in spite of my old rad being a Toyota one with the part number on the top.
After ringing around and finding the rad in stock but not with the top pipe my mechanics eventually found the right one so now I am up and running.
The final cost was £300 but that's what you get when something goes wrong with an LS, apparently main dealer cost is £311 just for the Rad, presumably plus VAT.
All I will say is if you are in the same position make sure you get the correct Rad, cos even after giving the part number on top of my old rad, it still wasn't exactly 100%.
My missus has a card displayed, it says,"If it has Tyres or Bollocks then you will have trouble with it"
:-)