I have one of those electric impact drivers that run off of the bike battery. It never fails to undo the rear wheel and sprocket nuts.
I just re torque the nuts when im doing them up.
I think that Halfords stock the breakers for about £15. I know its more expensive than the old scaffold bar routine but you can do it singlehandedly and dont run the risk of slipping off and ballsing up the nut or your fingers/hands.
DC.