I have got a job offer from London...!? HELP?

[Rihtak]

Hello Friends, i have a facebook friend from uk. When i was chat with him, He offered me a job that computer trainer for his kids. He offered me 5000pounds as salary per month and 200pounds weekly allowance. He says that he will take care of my flight ticket and visa charges and he says that all i have to pay 400 pounds for the working permit form to the travel agency. Also he said that working permit form is been issued by the government to the foreigner.
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Guys, I have completed my computer engineering and i can be a comp. trainer for kids. I came from a poor family. so i feel like this job offer will very helpfull for my life and my family. BUT, Is that all the information said by that unknown facbook friend is true???. I dont know anything about him and even he didn't ask me anything about myself too. He just uploaded some photos of his family members in his fb profile. I'm so confused and got some fear about it. How can i trust him..?? Please Friends Help me. What i should reply to him about the job offer..??? HELP..!!!