The UK is considered to be one of the costly states in the world. That is why most of the international students need to work in the UK while studying.
The UK allows the international students to work because the students are the cheapest workers thus helping the economy of the country by not only paying huge amounts of fees to the universities or colleges but also provide cheap and easily available labour force
If a student is admitted to a course lasting more then 6 months then the student is allowed to work for 20 hours a week. However, the employment must not be taken as full time. A student can only work as a part time worker but there is another option to work for full time on Saturday & Sunday of every week and if the student does not want to work during the semester times then there is an opportunity to take a full time job in the vacation for three months in a year.
Exceeding the limit of 20 hours a week during the semester times may cause serious problems to the student as this is against the laws of the UK Border Agency and this may result in the cancellation of visa and once the visa is cancelled than there is no other option but to leave the country.
More clearly, a student may be deported if found working in the UK for full time without any permission.
However, a student may work for more than 20 hours a week if the job is a part of the course of study.
But if a student has completed a degree course in the UK then it is legal to take some full time job. For this purpose the student must show proof of a completed degree course in the UK, a valid work permit and crystal clear immigration history
Students under 16 are not allowed to work as this is against the child labour policy.