I recently had my starter motor out and it was a bit of a pig of a job.
Mine had a bracket supporting the back of the starter and securing it to the block. This was difficult to remove as the space was very tight requiring slim hands, a good range of spanners and UJ's. I would suggest asking the wife to help therefore ! Also getting this bracket back in was worse.
Dont know why this bracket was even necessary as all other cars seems to just rely on the 3 bolts securing the starter to the bell housing.
I also had to remove the oil temp sender to gain enough wiggle room to manoeuver the starter out, which was also very tight. if you are further hindered by this obstinate bolt then I think you may not get the starter out at all without getting this bolt out first.
My car is an S3 with Air con and not sure if the procedure suggested here is the same as for all others.
This was an account of my struggle with the starter, for what it is worth.
Steve