Correct!

You lose control of your car and damage a garden wall. What must you do if the property owner is not available?

Report the incident to the police within 24 hours
Correct answer
Go back to tell the house owner the next day
Report the incident to your insurance company when you get home
Find someone in the area to tell them about it immediately

DVSA theory test explanation

If the property owner is not available at the time, you must inform the police about the incident. This should be done as soon as possible, and in any case within 24 hours.