Hi,
The DS1307 is a cheap and simple chip to use. There's a dedicated library, it has battery backup, have you thought what a power cut will do to your clock, reprogram it all again!! You can even buy a cheap DS1307 module from China for about £1.50 in real money, or $2USD post paid. It is controlled by the i2c bus so just 4 wires and 2 of them are power, includes backup battery CR2032. This has got to be the easy way.............
Hope it helps, Regards.
Mel.