Right now you have a low gear that is 3.63 gain ratio (49 inches, if you think that way).

Easiest is to change the freewheel. A 28-tooth big sprocket would get you a 2.98 gain ratio which is reasonably low. I imagine most rear derailleurs should be able to handle that amount of wrap.

Is it low enough? Hard to say. You could just do it and see. Or you could borrow or rent a bike with really low gearing (a hybrid like they rent to tourists, say) and go ride your favorite routes, see what is the highest gear you can comfortably use. Record that gear information (teeth on chain ring and on sprocket) as well as the other relevant info (rim diameter, crank length). Plug it into a gearing calculator like the one at Sheldon Brown's site and see what gain ratio you need for your Bianchi.

If needed, you could consider a smaller inner chainring (if your crank will accept it), a compact double crank, even a triple. Some of those start involving changing a lot of parts.

Obviously you will want to lose weight off yourself, build up your legs, etc etc, but you knew that already.