I'm looking at using the code to set a photo period, ie at a set time, say 11:00 pm lights go off, then at 06:00 am lights come on.

Is it a simple case of : (not actual code, more logic)

Code:
set off time
set on time

I2CRead SDApin,SCLpin,$D0,$00,[RTCSec,RTCMin,RTCHour,RTCWDay,RTCDay,RTCMonth,RTCYear,RTCCtrl]

If RTCHour=>off time or <=on time then lights off
Else lights on