As to the actual locations on the itineraries on these tours, any would-be ‘set-jetters’ should be aware that, often in films, what you see onscreen is not what you get in terms of story settings, even when film-makers claim to have shot on the “actual locations.” Here, the novel’s French and Italian settings are as often as not portrayed by English stately homes or by English studio mockups. (And, in the Biblical flashbacks, Palestine is Malta.) It may have been nervousness of the film’s perceived anti-Catholic theme that prompted the filmmakers to choose locations in Protestant Britain over those in Catholic Europe. And French President Chirac’s attempting to negotiate production co-operation in exchange for the filmmakers hiring his actress niece instead of Audrey Tautou, and for paying French actor Jean Reno a bigger salary, may have decided the director to film only the minimum coverage in France since he had no intention of adopting Chirac's 'suggestions.' In Britain, the crew actually ran into a problem with the Church Of England when Westminster Abbey changed its position about letting film cameras inside, for reasons either theological or financial. (The Abbey claims the former and co-star Sir Ian McKellen claims the latter.)
For anyone interested, I’ve put various images I have of the film’s locations (some from the film and some my own) onsite, together with an explanatory outline of what’s what: Da Vinci Code Locations Photos Guide.