I want to make a Home Automation System....I want to make a Software which will provide me a decent Interface on both Laptop & Android Phone.
OK. Lets take that as a specification.
In your home you have: Lights, heaters, alarm systems, doors, freezers, air conditioners, sound/video systems and so on that all need to be connected to the automation system.
Then you need some means to monitor and control that mess of stuff. Perhaps whilst not even at home. From the other side of the world. And, as you say, from whatever machine you happen to be in front of at the time: Windows, Mac, iPhone, Android whatever.
What to do?
1) Have all those devices in your home communicate with some central computer. That central server will be able to collect information from the devices and send commands back to them.
2) Have that central computer accessible to the internet. Either arrange that your home connection is accessible or use a server in a cloud service like Google Cloud or MS Azure or whatever.
3) Have that central control server run a web server. Via the web pages served up by that web server you will be able to connect using a web browser on any machine that has one and monitor/control you home.
What you need to know to make this work:
For the devices to server part: MQTT, I don't know depends on how you want to connect them.
Does this all sound very complicated?
And whilst we are here, the idea that Qt is to heavy for the Pi is certainly not true. I have Qt apps that run on the Pi just fine, including accelerated 3D graphics using GLES.
Memory in C++ is a leaky abstraction .