No they can’t reject, although I believe it’s 28 days notice needed to change the start date. Although my work were flexible and allowed less when I requested to change the dates
If using AL I’m sure it’ll be fine! I did the exact same and started my mat leave today at 36 weeks with 14 days of AL 🤩
I think you can but as others have said depends on your boss. Realistically nobody can force you to work when you are unwell. Alternatively you can get a note from the doctor to help your case. Good luck 🤞
Depends on where you work, but my HR needed 8 weeks notice when changing mat leave start and return dates