Yep mines on auto now, so next winter should be ok. But I needed that ruddy book to sort it. Very disappointed in myself. ?My nice modern car (11 years old) does it automagically. It's quite fun to watch it when the clocks go back, because as well as the digital ones it also has an analogue clock, and the hands don't go backwards, so the first time you turn the ignition on after the end of BST they whizz forwards 11 hours.
My previous car needed me to do it. I just left it on GMT all year round.