They normally use Interlink for their deliveries, you could ring your local interlink depot and give them the Dell Order Number and ask them to either hold it for collection or send it to another address.
If you are not home, the courier will leave a card stating that you can collect it at their depot. It will have a contact number for the depot on the card. If you have a friendly neighbour they may also leave it with them. You can track your delivery online also with your id and order numbers.
A neighbour received an order from Dell a few months ago, he was out at the time and the Interlink delivery person called to me (I happened to be home), so I signed for it and passed it on later.
Ah they are pretty decent.
I've had a few items delivered when I was not around and the delivery guy always rang to see what to do or who to leave it with.