He is wrong and hes treating you unfairly. you can take all your holidays before maternity,even add them on before your maternity starts. and its your choice to when you go on maternity- if you go early you will have to come back earlier remeber you may want that time with your little baba rather than speding it at home while your pregnant xxx not sure who you go to totake action agaist him...mabe get a print out of your rights and give it to him...think he's feeling bitter because your pregnant and get a years off what a douche lol
Supersquish and TriTread are right, you can take your leave as a normal employed person any time you like. Is there an HR department at your company? If so, it's definitely worth having a quite chat about this with them - they'll probably have a quiet chat with your boss (attitude adjustment!!). Otherwise you could ask them to be present in a meeting with your boss while you tell him why you feel that he's being unfair. That ought to stop him in his tracks and prevent the problem escalating.
If there isn't an HR department, you'll want to ask him for a meeting where you tell him that you think he's being unfair. Take notes, email him the notes after the meeting.