the only english people want is business english! whether or not you have a qualification doesn't play a part really. some want TEFL but the demand is soo big is doesnt matter.
i had never seen business english before. i just sat there with the course book and thought on my feet, not hard if you have a normal level of intelligence. fact is they will take you because you are a native speaker, they would take a bum american (brits are more favoured ) over a super qualified russian teacher with years experiance in a heart beat.