As load on the relay is bulb and I assume that you don't have any timing constraints so you can use any general purpose relay.
When relay is in off state NC gets connected to COM and when relay is in on state NO gets connected to COM.
Expansion of these terms is:
NC = Normally Closed
NO = Normally Open
COM = Common]
More Explain
That sort of arrangement would be much more economical on batteries,
however any current through the LED also flows through the limiting
resistor, so to keep this fairly low, how about making the supply
voltage 4.5 volts, three cells, that means the limiting resistor
would be using less power than the LED rather than more with 9 volts.
Also if you cross couple between the collector of the second transistor
with a high value resistor back to the first transistor, then you get
a slight "schmitt" effect and the LED should switch on rather than
wind up gradually. This could save a little on batteries too as it
would only come on when needed
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