Tier 4 (General) students can work if they study at a higher education institution (HEI) or an overseas HEI. Aa an HEI student ( at level 6 or above) you are allow to work 20 hours per week during term time and full time during vacations .

In order to work in the UK you need to have NI number . It  is a unique personal number which is used to record your National Insurance contributions. You do not need to have a NI before starting work, but you must obtain one when you get a job. You can apply for a NI by calling 0845 600 0643 to make an appointment. Your appointment will take place at your nearest Jobcentre Plus office, or Social Security office in Northern Ireland. 

As per the government rules , the minimum wages/hour for students are as below :- 

Year 25 and over - £7.20

21 to 24   - £6.70

18 to 20   -£5.30

Under 18   -£3.87 

Find Part-time Student Jobs in London

There are thousands of part-time student jobs in London to help support your studies. Many universities have careers and work placement centres to help you find employment. You can also search online job ( link )

Work after study 

Non-EU students who wish to remain in the UK after they have graduated must apply for a work visa.  There are several visas you can apply for as a London graduate:

• Tier 2 (General) Visa: This is the primary visa to remain and work in the UK after your studies. It is open to recent graduates with a Bachelor’s, Master’s or PhD from a recognised UK university. Before you apply you must have an offer of a skilled job from a licensed employer and be paid a salary of at least £20,800. After five years of employment, Tier 2 visa holders can apply for indefinite leave to remain in the UK providing they meet the salary requirements (£35,000) and other relevant eligibility criteria. Visit the UK Home Office website for further information.
• Tier 1 (Graduate Entrepreneur) Visa: This visa option is open to all students who are developing a world-class business idea. You will need to be identified and sponsored by your university as having the potential to create your own business in the UK. This applies to all graduating students from any subject discipline.
• Tier 1 Entrepreneur Visa: If you are a student and want start your business in UK and willing to invest £50000 to £200000 over the initial period of visa then this visa is for you.
• Tier 5 Youth Mobility Scheme: Some nationalities are eligible to apply for a two-year work scheme permit. You can find details on the UK Home Office website.
• Tier 5 Temporary Worker: This visa allows you to work in the UK for up to 12 or 24 months (depending on the scheme you’re applying for). International students in the UK can apply for the Tier 5 (Government Authorised Exchange) visa to undertake work experience and internships in the UK after their studies. You can apply to switch from your Tier 4 visa to this visa from within the UK.