Felling something is in my throat of left side, swelling on neck under the jaw left side, tiny blood on gargle, (31+smoke+drink) how common cancer is?

Not common at all at. At this age, very unlikely. Yet you need to have a medical exam since you very likely have an enlarged lymph node in your left side of the neck, . This needs to be checked out if it does not go away over a period of 3-4 weeks.