Hi Doctor Ive Got A Bad Chest Infection And I

Hi doctor ive got a bad chest infection and I have coughed up some green phlegm but now I'm coughing to try and get it up and it's not shifting I need some antibiotics I'm totally fine taken antibiotics either amoxicillin or penicillin would it be ok to take penicillin vk 250mg tablets to help me get better will they work can you let me no asap please thanks