Although not a pilot (yet!)...I have around an hour (no traffic) commute to work everyday...I am on the M4 heading out of London so traffic is usually not too much of a problem.
M25 as everyone has said is a right mess...Driving in slow moving traffic can really get to you after a few months, so that is something to bear in mind.
I have been doing this for around 6 months and am usually not too fatigued etc, but I would recommend staying local to begin with, as with any job, airline pilot or not, you can not afford to be getting into work late. You have to almost double the estimated time to begin with, to get a feel of your journey.
I honestly do not think I could do this long (long) term anyway...Was a job I wanted, so have to put up with the commute.
Good luck
