Boilermate BP with BG UT2 timer

My Boilermate 2000 had the dreaded internal leak so BG came along today and fitted a shiny new Boilermate BP. They have however wired a BG UT2 timeswitch to it. The installer says I can time when I want hot water but surely this negates the need for a Boilermate in the first place. Anyone got this combo and what are the best settings ?

Thanks