See this link for advice - https://personal.help.royalmail.com/app/answers/detail/a_id/317/~/i-think-my-mail-is-lost---i-havent-received-my-delivery-yet
APC Delivery - Please contact us if you have not received your delivery within 3 working days. APC will leave a calling card if you were not in to take delivery.
MyHermes - Please contact us if you have not received your order within 5 working days. Check with neighbours that your parcel has not been left with them.