It takes me about 10 - 15 minutes by the roadside, depending on how cold my hands are (if you're going to puncture it'll be at night when its cold and teeming down with rain) and how tight the tyre is on the rim. I always carry at least two tubes and don't bother with patching by the roadside.

I bought a couple of sets of Schwalbe tyre levers a few months back; they really do make removing and replacing recalcitrant tyres a whole lot quicker and easier, even the Michelin Lithions which broke two normal levers the first time I tried removing one.

I have frame pumps on all my bikes; they don't make inflating a tyre a pleasure but they are a whole lot quicker than using a mini pump.