Nerdboy
Do you guys think it is a good idea to apply before b-school?
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Also, what happens to this thing if I suddenly depart for a year in, say, a small French town, instead of the UK?
A close friend of mine got a Tier 1 recently. You're correct on the 3 years length.
The Tier 1 won't be very useful to you now. You basically forfeit your visa if you spend 6 months out of any 12 month period outside of the country, which you would have to do in order to study. You'll have to check the exact details with respect to days per year and what counts as a day, etc.
Also, when you enter the UK on a work permit the custom officer will usually question you about your work situation and can make life difficult if you're not working in the UK. This depends a bit on your luck and I'm still not sure on the exact consequences of not working. As you noticed the Home office is often WAY too vague on this stuff. You'll need another visa (Tier 1, employer sponsored, etc.) after your 3 years if you want to get Permanent Residency, which I believe requires 5 years of residency without leaving for more than 6 mo. in any 12mo. period. (Some countries have lower requirements.)
Your best approach might be to apply for the HSMP a few months before you want to come to the UK. That way you can claim previous earnings from when you were still working in order to get your points and you can put HSMP on your CV. For a
typical job search in the UK this is essential, because most industries will just ignore a CV without a work permit. On top of that employer sponsorship obviously ties you to your employer, which is never really a good situation.
Having said that, big MBA recruiters like banks are set up to have their HR machine churn out an employer sponsorship for you with relatively little hassle, so that shouldn't be a problem. It may be different for botique firms, but networking will probably help there if you don't yet have a work permit. I've had a number of friends get sponsored and they all worked at their employer under other visas (student, etc) before getting their sponsorship.
A small tip: If you really do go for the HSMP and apply while in England then go to the Sheffield office, not the Croydon (London) one. When my friend went they had never done a Tier 1 so they erred on the side of approving it. They appear to be less organized and more lenient than the overworked Croydon office, which means you'd probably have less trouble obtaining a visa.