DaisyAnne if you have a gas or dual fuel cooker, most gas burners on the hob can be lit with a match or independent gas lighter.
If you have any kind of solid fuel stove, once the fire is going you should be able to use the top of it like a hob and boil kettles and even cook a casserole on it. Kettles are slower to boil, but it can be done.
You could buy a small camping stove, but this is safer used outside. If you are using a paraffin or calor gas heater, they too usually have flat tops that you could put a hob kettle or saucepan of water on.
You can wrap baking potatoes in foil and cook them in the base of a stove, put them in the ash tray, or push them well into an open fire and cook them that way.
If you know a power cut is coming you could start cooking a casserole in a slow cooker and when the power cut starts unplug it wrap it up in towels, cushions, a blanket or old quilt so that the heat is kept in and it keeps cooking, like the old hay box.