Apply for a Tier 4 (Student) Visa

You are eligible for UK study if you have secured an offer of tuition from a UK educational sponsor listed on the current register of sponsors.

Work activity is restricted in the Tier 4 category, but those studying at degree level or above at a UK university will be able to work 20 hours per week during term time and full time during vacation periods.

Extensions are possible, but generally only where a student can show academic progression. In most cases, this means moving from one level of a course to another; for example, from a Bachelors degree to a Masters degree.

Yes, Tier 4 has a specific child sub-category that allows for this. Again, sponsors must be approved and entered on the register of sponsors, and child applicants will additionally have extra requirements to meet relating to their safety and welfare in the UK.

Tier 4 graduates have some preferential provisions which allow their switch to Tier 2 work. For example, their prospective employer may not need to advertise the position to the wider job market, and they may qualify for a lower salary than another more established applicant. However, it is still necessary to secure a job offer from an employer listed on the current register of Tier 2 sponsors, and for that employer to issue a Certificate of Sponsorship.

This really depends on the qualification for which an applicant is studying and the time during which they have already completed UK study (there is an upper limit in the Tier 4 category). Note that Tier 2 specifically caters for those employed in postdoctorate positions, including many research positions.

Short-term students have no basis on which to apply to bring their dependents to the UK. Tier 4 students can so this in some cases, most commonly where they are Government sponsored, or where they are completing degree-level study over a long period.