This is the basic explanation:
Paternity Leave & Pay
The right to paid paternity leave under the Employment Act 2002 is in addition to the 13 unpaid weeks' parental leave entitlement. The entitlement is two weeks paid leave. The leave is paid at the same rate as Statutory Maternity Pay, £108.85 per week (or 90% of the employees average weekly earnings if this is less). An employer is entitled to reclaim Paternity Pay from the government.
Leave can be taken in a single block of either one week or two weeks. It can be taken after the birth of a child or the placement of a child for adoption. The leave must be taken within 56 days of the expected week of childbirth or the actual birth, (if this is earlier).
Statutory Paternity Pay and Leave is available to employees whether they are the biological father or the mother's partner or husband, but not the biological father.
Entitlement begins if the baby is born or placed for adoption on or after 6th April 2003.
Paternity Leave is available to an employee who has completed a period of at least 26 weeks qualifying service with the same employer, by the 14th week before the child is expected to be born (or is matched in the case of adoption). Additional conditions are that the mother must have given appropriate notification and qualifies for Statutory Maternity Leave.
An employee is entitled to the same job following paternity leave and will be protected from unfair dismissal related to paternity leave.
Employers can reclaim Statutory Paternity Pay in the same way as for Statutory Maternity Pay. If an employer fails to pay Statutory Paternity Pay, the Inland Revenue will become responsible for the payment. This is also the case if the employer becomes insolvent.
Basically, if he's worked for the same employer for more than the first 6 months of your pregnancy then you should get it!