Getting a Job in England or Australia when I don't have a visa or work experience?

Hi guys I am a BBA student from Karachi, Pakistan and the fact is that I don't have any work experience or a visa at the moment but want to get a full-time job in either England and Australia. So I wanted to know what is the process to get a job when at the moment I don't have a visa or work experience because some people I ask say that you first apply for a job and if the firm hires you then it sponsors you and you can the get a visa but most job sites I go to state that you must already have permission to work in either UK or Australia or demand experience. So can anyone please clear this matter up and give me guidance?