There has been a lot of news in the press over the last few months warning people against Unscrupulous driving instructor schools which are taking advantage of people who have been made redundant or have been hit hard by the recession.
They promote themselves and talk about all the great money you could get when (IF) you qualify, but the costs of taking the course(s) can be very very high and if the stats are to be believed then the number of people taking driving lessons is actually falling. So your paying thousands for a course that you have no guarantee of passing, to enter a market which is highly saturated and in decline at the moment. If anyone is making outrageous claims or guarantees make sure you get it in writing and if they wont then think about why they refuse to do it, probably because they know they cant guarantee it.
So make sure you do your homework, dont believe the hype and remember google is your friend.