Thanks for the reply.
I've since had the car on vagcom which confirms an issue with low Air con pressure. I'm certain it's the radiator that has a leak, probably as a result of stone hit. The fluid on the grill is the a product of the gas escaping.
Boost etc is normal and the car is driving fine.
Just pricing up an air con radiator now. Doesn't come cheap unfortunately!! Anyone recommend good quality item other than the VAG part.
Thanks