In previous years it was quite difficult to find a job in England, so the easiest way how to start working there was to became an au-pair. The usual au-pair job is paid by 45-50GBP per week.
You might think that au-pair job is not favourable these days, but since we are EU members so it's very favourable even for people who are coming to the UK for the firt time.
If you don't have any experience with job in UK, au-pair is great choise. You will became familiar with the environment and then you can find another job. There is always someone who is looking for help in bar or kitchen.