Yes Royal Mail Tracked orders can be left in a Safe Place you can specify a Safeplace (in less than 30 characters) in the Order Notes box at Checkout. Any orders left in a Safeplace are left at your own risk; if the goods are lost they will not be replaced.
This service is not available on Royal Mail Special or Saturday Deliveries, or Delivery by Courier. You will receive an email from the Delivery company where you can select a different delivery date or a Collection point if you think you are not going to be in to receive your order. You will usually be offered a second and third delivery too.