I average between 130-160 miles per week commuting (I work at several sites during the week)

One of my clients lives just over 20 miles away from my home, and that takes me just over an hour of cycling to get there, but I have no hills, and although I have a long section riding through the city which slows my time down (lots of stops), the rest is on a cycle path that runs adjacent to a guided bus system (a really good cycle path with long stretches where one can travel at speed.

I'd love to have some hills (it's very flat here in Cambridge UK) but we have strong winds here. If you do decide to commute daily by bike, you will get superfit with the hills you have.

if you don't want to cycle the whole way (especially if the weather is bad), buy a cheap bike and a good lock, and get a bus (or drive your car) .... to somewhere along the route where it's safe to park your car and hop onto your bike

I have a friend who has 3 cheap bikes locked up in various parts of London .... he commutes by train, and depending at which station he is hopping off (or which part of London he needs to work), there is always a bike to continue his journey