I also see people quoting extortine main dealer service costs in their calculations.Depending on the car independent specialists are fully brand trained and in many ways do a better job than a main dealer and also cheaper. There are also respected back street garages that are also far cheaper than a main dealer. Its a different scenario if you buy new, but most offer service packages that reduce the cost. It is also allowable to take a new car to VAT registered garage, as long as they use genuine parts the warranty remains.
It’s also worth noting that many manufacturers / franchised dealerships offer heavily discounted services for cars that are 5 years old or over. These often include free breakdown cover for the year and a discount off the MOT.