Brake disc thickness measured

MoinMoin and Hello, I would like to be the new one at the Volvo XC60 Forum and intend to buy tomorrow afternoon an XC60 model 156 D5 (220hp) with only 45,000 km on the speedometer, EZ 2016, for at least 33.800.- €. On the stage the brake disc thickness was measured at the front with 27.5 mm, at the rear with 21.2 mm. My question, how strong are new brake discs and what strength is considered as a wear limit for changing? As the price seems a bit happy, I would like to judge how short-term (of course This is due to my driving style and other factors) the replacement of brake discs and possibly brake blocks, oh yes, residual thickness of the blocks 6mm, to come to me. Who knows short-term data and or advice? Greetings from the southern North Sea Bernd