Parental leave is unpaid. Although some employers may pay you during this time, there is no legal obligation on them to do so, unless this is part of your contract of employment. If you do not get paid parental leave and are low-paid, you may be entitled to extra social security benefits while taking leave.
To check these rights, contact, a specialist advisor such as Citizens Advice.
Tax credits are being replaced by Universal Credit for most people. You can find out more on the Gov.UK website.