The only thing that you can do at present, is to wait and see how things progress.Larger items via Parcel Force or other couriers should be okay.Smaller packaged Royal Mail items, may be held up slightly, but it being so near christmas [bonus and overtime, come to mind]I cannot see any extended postal delays.
If your order was shipped by Royal Mail LetterPost (your order confirmation email will confirm this), please note that it can take up to five days for delivery.
If your order hasn't arrived after five days have passed, we can enter a claim against Royal Mail for a lost delivery. This would include Royal Mail writing to you to confirm non-receipt of the order, which is a form you need to fill in and return. It is important that you complete this form and return it.
Once the five day delivery time has been exceeded, we're able to offer a replacement order or a refund and our customer services team will arrange this for you.
To report a missing or late delivery, please email [email protected] using "Letter Post Delivery" in the subject line of your email.
Can you explain in light of what you have put above.?