maternity

[Bankyamy]

hi everyone,
am due to have my baby on the 2/01/17, I haven't been feeling well and currently on sick leave but have booked off four weeks holiday from the 2/12/16 (four weeks before my due date), my fear is this: will my sick leave override this annual leave. can they cancel my annual leave and ask me to start my maternity leave instead?
I have checked over my contract and there is nothing there mentioning sick/holiday during pregnancy.

If you were off sick at/beyond 36 weeks they could trigger your maternity leave. However you're planning on being on leave from this time, so there would be little point.

Any sick leave until this point should not result in pressure to bring coward maternity leave.

If they're sensible (& don't want to deal with the sticky situation of you having annual leave left over etc) they would let you come to work/be off sick until 36 weeks. Then your annual leave (have you pre-arranged this with your boss/HR?) would kick in.

It would be to your employer's advantage to permit you to take your booked 4 weeks holiday leave before your maternity leave starts.
Otherwise (e.g. if you were still off sick for those 4 weeks) they would be obliged to carry those 4 weeks of holiday over for you to take after your maternity leave ends, in addition to the holidays that you will continue to accrue during your maternity leave.
Although (as Itscurtainsforyou correct says) they could trigger your maternity leave start from 2/12/16, it would be to their financial and organisational detriment to do so.
Perhaps, if your concern is that you you don't want your maternity leave start date brought forward, you could inform your GP that you don't need a fit note from 2/12/16 because you already have holiday booked after that date.
If your concern is the amount of sick leave you are taking (because of your employer's absence policies) don't worry. Only an employer wishing to invite a discrimination claim would take any kind of action against an employee who is off sick due to a pregnancy related illness.