UK Delivery Tracking

Hi everyone, I have received an email saying my laptop is going to arrive tomorrow 8am-6pm. However, I won't be at home the whole day, so I'm thinking whether I can confirm a specific time slot?

I have tried the DP world website and it doesn't work. Some say the delivery company is DHL so I tired that too but the reference number (I used the order number) is not valid.

Any idea how to track the details of the delivery? Thanks a lot!