I have an 07 diesel A6 and the coolant is getting low so I want to top it up with coolant, particularly as we're now in winter.

I see that I can only use G12 coolant, which Halfords don't sell. I'm stuggling to find the correct stuff online. Can anyone recommend where I can buy it from? Also is G12+ the same as G12 or do I have to only use G12?

Thanks