The law makes an exception for the temporary use of Spare wheels (Space savers) fitted in an emergency. Temporary use Spare wheels are narrower than the standard size car tyres and could well be of different size to the wheels currently fitted to your vehicle, however this is acceptable also for example fitting a 16” or 17' spare wheel to your car which has 18” alloys is fine to use.
Space-saver spare wheel are designed for temporary use to enable the vehicle to be driven home or/and to a place of safety/repair. There is no maximum distance however they do have a speed restriction of 50mph.