Range from the cheapest window sill replacement £260 (TTM Improve Homes based in UB5) to the dearest window sill replacement £456 (T M Builder based in UB4).
Comparing carpenter and joiners estimates for replacing a window sill gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to replace a window sill in Northolt by posting a job with HaMuch and we will send it to carpenter and joiners in Northolt.

"To install indoor window boards in four rooms including 3 Bay windows."
UB6