National Insurance Number
more information on
http://direct.gov.uk or
http://jobcentreplus.gov.uk
You need to have job or job offer with start date to apply for NINO.
One word of advice, the
longest waiting time for the letter (the crad is secondary once you have the letter with number) is experienced in
LONDON. Ignore any advertised admin delays. If you can, go to smaller town to sort NI. Problem is, it's based on 'address'. It tends to be pain even get through one of the few lines to book appointment, in London.
One way to go around this is to pop in to city (Edinburgh was good, fast when I organised it for my friend couple years ago) where you fake interest in agency working, register with agency for whichever casual jobs, then you've got 'job' for NI application.
England is generally worse for sorting 'proof of address' for opening UK bank account, but doable. One easy way, but lengthy, is getting basic 'cashcard' account, opened by post. No need to work, put college student or whatever, copy of passport, voila. Then wait couple weeks to get it all done. OR, pay to HSBC or Barclays for 'premium' foreigner targetted account to set up without proof of address initially.
Anything official, letter, even from your bank abroad can help with that.
Companies shouldn't discriminate jobseekers due to lack of NI/bank a/c organised, but they do.. All of this can be arranged shortly after starting job. They'd not get you proper tax code straight away anyway.
More specific info on 'setting up' in the UK, PM me, can give pointers.