Baby bodyclock adjustment 18mth

Baby used to sleep at 8 plus , latest 9pm at night . But her father always come bck home late at night and woke up her to spent some time with her despite me emphasizing on the impotency of her body clock and rest . As she have to attemd playgroup and i have to get her ready by 7.20am. Im a FTWM . nowaday, she will only want to sleep at 11 pm plus , 12am , and will wake up only at 11am plus . How do i adjust bck her sleep timing as its affecting both our lifes . :( im missing out on work becus of this . She will get super cranky and only want to latch if i just woke her up before 11am .. Anybody going through the same situation ? Please advise ..