2.5 tdi intermittent failure to crank

Hi All, I have an ongoing intermittent failure to crank. I can get it to crank and start by just using key and repeatedly switching off and re trying. I feel this eliminates the gear position switch and I am thinking it may be starter solenoid/starter. I plan to try to access the solenoid connector and put a bulb in circuit to establish that the column switch is not at fault. If it is the starter is it under tray off, bumper off, lock panel in service position, alternator off and finally starter motor or can it be done easier quicker?.

Regards Jimmy