Hello Keith,
Thanks for joining.
If your car has only done an average of 4K miles a year, then your cambelt has had a hammering ( as we say in Wales) unless your mileage has been covered in irregular long trips.
Short journeys, and particular if stop/start is engaged, will result in higher than normal stresses on belts, so yes, it does need changing at the 5 year interval.
I would recommend you also have the auxiliary belt renewed at the same time.
Kind regards,
Gareth.