Seat Leon intermittent starting problem

I have a 2002 SEAT Leon Cupra 'R' (210) and have been having intermittent starting problems recently. I unlock the car with no problems, put the key in the ignition and when I turn to the first stop the dash lights etc come on as normal but when I turn the key further the lights etc still stay on but nothing happens. I mean nothing, not even a click. If i turn the key back and forward a few times then it eventually starts and runs fine. I know this is a common fault on VW group cars but is it more likely to be the starter motor, wire to the starter or the ignition switch? If it is the ignition switch can it be replaced without taking the steering wheel and airbag off?