Two things.
1) it's not the distance, it's the reliable distance. I used to work in the middle of Manchester; trying to get there for 8:30am is a whole other prospect to trying to get there at lunchtime. In good conditions, it was about an hour; in bad, who knows, can be twice that, or more. Do you want to be leaving the house at 6:30am in order to not be late (usually), and be there an hour early half the time?
In the end, TomTom Traffic was the saviour of my sanity; it could tell me if the motorways were ruined so that I could take the line less travelled. I'd suggest that if traffic is likely to be an issue, you either need a Flexi-time agreement, or an understanding that you're going to be late occasionally.
Course, if your commute is pedalling down the canal, it's a bit of a moot point.
2) The longer the commute, the less you can realistically do it for IMHO. I got to a point where I was leaving at 7am to get to work for 8:30, hanging back for an hour after work to let the traffic clear and then getting home at 7pm or later. That's 12 hours of the day gone on a good day. I did it for four years on the back of commuting even further to Warrington for two years, and it left me knackered.
I took a pay cut to be where I am currently, but it's a 15 minute drive to work. I can fall out of bed at 8 and be in the office for 8:30, come home for lunch, and have my evenings back. What's that worth? I think now if someone offered me five grand on my salary to go back to that commute I'd say no, and I'm broke.
So, yeah. Personally I'd say that if you're going to be taking the long commute option then take it as a shorter term prospect with a view to moving / changing in a few years.