I had the mesh grille fitted from new - stops stones damaging the radiator, looks good and also I use it to fasten my badges to the car - no more than four at a time - does not seem to affect the cooling.
If you are in MSCC put a small add in Miscellany - someone may have a spare. Otherwise most dealers would have one.
Likewise take Paul`s advice & fit an aluminium radiator - Sifab or Mulfab both do them and are excellent keeping temps down and very strong fixings etc. the original rads were made for cars which do not flex - -so the plastic pipes tend to crack after a while - knowing my luck it would have been in the middle of Dartmoor, in a blizzard with no phone signal - so better safe than sorry and invested in ali. rad before it was needed. I have not regretted it - in the four years or so since fitting the fan has only cut in on three occasions - all in a lengthy stop/start queue for over fifteen minutes. Mines on a 4/4 Sigma engine by the way.

2010 4/4 sport - le mans green