Hi Andy,
I had exactly the same thing start last week when the weather turned very cold.I had it back to the dealers,and it turns out it is the diesel fuel pre-heater that is clicking/ticking.This heats the fuel on cold mornings to aid starting and enables the cabin to warm up quicker as well.It also runs the auxillary heater system as well if it is fitted.You will have had a remote control to use if your vehicle has this fitted.I think a lot of people will be caught out by this noise,as,like you,i was quite horrified at the sound emminating from the passenger side front area.The dealers couldnt answer my questions right away,but as soon as i booked it in,they said,"Oh Yeah", its the diesel fuel pre heater.It should point this out in the manual as well,but i cant find anything in the manual about the operational clicking noise.So there is nothing to worry about,its supposed to do it,and it is temperature activated as well,hope this helps,regards, SIMON.