I'm 3 minutes from a canal, but I'd only fish it under armed guard, and 5 minutes from the Trent, which has plenty of roach, dace and perch but the bigger fish only feed at night and in the right conditions. It's good for a couple of hours evening fishing early season. I almost invariably drive over both on my way to more attractive places.
Within 30 - 40 mins drive I've got some great Trent stretches, the Derwent, the Soar and the Erewash, together with some good stillwaters and four canals. Most of my fishing takes about half an hour to get to, though I don't mind occasional expeditions taking an hour.
It's hard to generalise about travel time. Early or late in the day, I can get to a venue 20 miles away in half an hour. Catch the traffic wrong and it will take an hour to get home from a lake 8 miles up the road.