Coolant Level...

Hi everyone,
While just doing a check over of everything in the engine bay earlier on (engine was cold) I noticed that my coolant level was around an inch away from the cold line.

So, I want to top it up but I only have the green coolant that I stick in my Renault Clio. The stuff in my RR is orange. Can I get this coolant from Halfords or somewhere like that or is it a dealer trip?? Ive read that its different stuff than the green coolant as I have an aluminium engine?? Is this right??

Thanks
-Wills

if its only a little bit down from the max, just top it up with water

Early p38's used the green coolant and late ones use red but they all have the same engine so i wouldnt worry, if you want to top it up with green, a little isn't going to hurt it