hi,
A timer circuit could give you a 5 second ON delay, with 1 second Light/ON period.
In addition to the 555 timer you referred to, you would require a small DC psu to provide power for the timer and the relay.
The relay would switch ON/OFF the lights.
If you use 'black' light lamps, as I understand it, they are flourescent type tubes/bulbs.
If I am correct I think you may have a problem trying to get 1 second flash.
They tend to 'flicker' when powered ON and they take a few seconds to reach maximum light intensity.
A standard tungsten lamp would be OK.
Does this help?