If you replace an old incandescent bulb with a modern LED one you will likely get a whiter light, cooler to touch and less expensive to tun.
However, sewing machines generally don't use much power, it's the appliences which get hot which consume greater amounts of electricity; irons, kettles, toasters etc.
As a general guide something with a 3amp fuse uses a small amount of power, something with a 13 amp fuse uses a lot and anything hard wired (cookers, fires) gobble it up.