Thanks for the replies. I decided to ditch the dealer and got the parts from TPS. Came in at £200 for the timing belt kit, water-pump, aux belt and 2 x 1.5L coolant (G12 evo).
I also noticed water in my tailgate last week. Turns out it was a perished grommet/pipe. That was £5. Part number is 510-827-861 if anyone else has the same issue.