Originally Posted by smcquie

Are a grey area person (I have a work permit) you need a National Insurance number (NI number) which is sort of like a SSN - your taxation gets tracked by it as well.
When I applied 6 years ago, you had to do it in person at the social security office closest to you - though it can take weeks to get through on the phone, then several weeks to get an appointment. Persevere, because you need this number to work (though you can start work without it - they give you an 'emergency tax code' which means you are charged at a slightly higher rate because you are not 'known' - don't panic, you get the extra tax back in the first pay packet after you have provided your NI number.
Have a look at this link, it should tell you everything you need to know: