I think you're right. Anyone who can afford the £700k price tag will almost certainly have more than one car. Then we can assume at least one tradesman per day, possibly grocery deliveries, postman, inevitable maintenance of utilities - water, power and the ubiquitous BT Openreach, meter readers, refuse lorries, recycling vehicles and that's before visitors, family, nurses, doctors...
Going to be a tight squeeze and not what you'd expect for that amount of money.