Written this before but many of the colleges only do half day lessons some very early some late in the evening so people can hold down a job.
But as you say I know that many schools have been inspected in London and many are now appealing as the inspectors marked them down which means most likely they will not be able to assit people with visas etc.
Although it seems many get a second chance to be regraded so will probably scrape though.
My Wifes first manager was on a student visa. Unbelivable amount of study at any time, work the rest of the time. But ten years is a little long i think for anyone, but they know if they can hold on then they are sorted..