David49
If a boiler is 10 yrs old parts should be available for repair unless it is some kind of obscure system .
Hot water systems usually have a back up system like an immersion heater you can switch on.
To have an immersion heater you need to have a hotwater tank. Many people now have Combi boilers that are like a central heating system and an old fashioned geyser rolled into one. These do not have hotwater tanks, so do not have immersion heaters.
We had a winter when we were without a gas supply for a fortnight. We had a combi boiler. As others suggest above we would go to the local swimming pool every other day for a shower and hairwash.
alternatively, your local leisure centre or a service station that has showers? 