Most autostores carry heater hoses. It may be in bulk on a roll. You just tell them what size and how many feet, they cut it off for you. You can take piece of old hose to show them. With old hoses, I use a utility knife to cut hose over fitting then peel the hose off the fitting.

You can usually route a used hose between the outlet and the inlet on the engine, bypass the heater core. You won't have a heater, but, may get you out of a bind till you can fix-it correctly. I'd have to look at your system to see if it would work.