Dear Sir/ Madam,
I am writing to apply for the job you advertised in today's newspaper Praca za granicą. My name is(imię) I am (wiek) years old and I come from (miasto), Poland.
I am a student at (nazwa szkoły). I have been learning English for (jak długo) years. Last year I passed FCE exam with a very good result.
Since I have some experience in working with children, I decided to apply for this job. Firstly, I have a younger sister and a younger brother. They are much younger than me and my mother often asks me to take care of them. Secondly, I have worked as a babysitter for 2 families. The children's ages are from 2 to 6 years old. The families were very satisfied with my work and gave me very good references.
In the next two months I have summer holidays at school, so I am able to come and stay at your house in London. I have been abroad before, so I'm not afraid of travelling alone, I am also prepared to leave home for 2 months without feeling homesick.
I am looking forward to receiving your reply.
References on request.