@Jadey
I have a 37 mile commute. It is 45 minutes in at the start of an early early or out at the end of a late late. But if I have an early late or a late early I end up fighting with the normal 9-5 office worker traffic. And there is always the chance they will close the motorway in the dead of night for resurfacing. I cannot recommend it. If circumstances didn't dictate that I have to stay living where I am, I would move to within walking distance of my depot.
Incidents have a tendency to happen towards the end of a duty, particularly long duties, because that is when drivers are most fatigued. A 45 minute commute turns a 9 hour 15 minute duty into a 10 hour duty. If you are 45 minutes away from depot, pretty much every duty becomes effectively a long duty.
In turn, this means that to compensate you have to be better rested before starting your commute than a driver who lives closer to the depot would. So not only do you lose 90 minutes of your life every working day in commuting, but you also lose a few minutes extra in sleep too. One of the draws of train driving is the amount of free time a driver gets. Commuting wastes this.
So in conclusion, congratulations indeed on your job offer! Definitely do not let your commute put you off accepting the offer - it is a great job / lifestyle / surprisingly-well-paid-passtime. If you have to stay put where you are, you WILL be able to live with it. But if you can, once you get that key and pay scale, use the newfound friendliness of bank managers to put a mortgage down on a small palace near the depot!