If you have the boiler at 75°C, the hot water will be coming out of the tap at about that temperature, which is much too hot - almost dangerous. Shower temperatures are about 40°C and bath temperatures even lower. The water in the cylinder needs to be at about 60°C to prevent the growth of Legionella.
I would seriously consider installing a cylinder stat and valve. The boiler would still be left at 75°C.
I would seriously consider installing a cylinder stat and valve. The boiler would still be left at 75°C.