Brave Descision, yet many poeple are changing careers, even a major vocational one like yours.
Henley offer a very good and above all pragmatic MBA, many attendees are from corporates but there are many from Small and Medium businesses. And the major conclusion we took out of the MBA before starting our business was that it doesn't matter if its a car company, a chocolate, a macdonalds, a biotec, a trucing company etc its all the same under the bonnet. Business is Business with Sales at the top line and your net net net profit at the botom, so an MBA is designed for big corporates but suites small businesses just fine.
Good luck,
MbaBible.com Team