The UK maternity employment laws are:
All pregnant employees are entitled to 52 weeks of maternity leave, this is made up of 26 weeks of ordinary maternity leave and 26 weeks of additional maternity leave. You can find further information here.
You must tell your employer 15 weeks before your due date, when the baby is due and when you want to start your maternity leave. Your employer may request this in writing. Your employer must then write to you within 28 days to confirm your start and end dates for maternity leave.