It looks like you want a "street light" that turns on at dusk and turns off at dawn and operates from AC mains power. Plenty of these lights already exist on the commercial market. Some even have passive infrared (PIR) motion sensors to turn the light on during the dark time, thereby saving a lot of electricity lighting up an area where no one is present. Your "proof of concept" circuit is a good start toward understanding the requirements of a dusk-to-dawn street light application. It satisfies the three design considerations listed below to demonstrate proof of concept, but it is not suitable for control of a higher intensity light.
what if i use a tubelight?
If you mean a tubular fluorescent light with a ballast, these are not generally suitable for outdoor lighting because they are difficult to start at low temperatures. An electronic ballast can help alleviate starting problems, but why would you choose a tubelight is lieu of any other luminary, such as an incandescent lamp, a white-light LED array, a low-pressure sodium-vapor arc lamp, or a mercury-vapor arc lamp? Any of these can be operated from relay contacts with proper supporting circuit designs.
So, to continue your public street light design effort, you need to consider how you will implement the following three requirements:
(1) You need a power source. Clearly a 9 V battery is insufficient. A mains power supply is required. You need to specify the power and voltage requirements of the luminary you choose.
(2) You need a means to control power to a large, powerful, luminary suitable for use in a street light. Perhaps an LED array will suffice, but you need to specify the luminary you intend to use. This control should be efficient and not dissipate a large amount of power. A BC547 with a current-limiting resistor is not going to work for reasons others here have mentioned. Since this is an on/off application, a relay might be the best approach, along with appropriate control circuitry. Other solutions for power control are also possible, such as TRIACS, SCRs, IGBTs, and MOSFETs. You, as the designer, must decide which method of power switching is appropriate for the luminary you choose for your street light.
(3) You need some means to sense when dusk arrives, and perhaps the same means to sense when dawn arrives, to control when the street light turns on and off. A light-dependent resistor (LDR) may or may not be the best choice for that, but they are commonly used for this purpose. This device will serve as an input to (2) above, which as previously mentioned by others here, will implement hysteresis to prevent unstable operation when transitioning to dusk or dawn..
Good luck proceeding from your "proof of concept" circuit to a practical and efficient street light. It will be an interesting journey and you can learn a lot by studying how it has been done by others. Google is your friend for this.