UC50 - Mail Handling Site A Wolverhampton christmas opening hours?

Does anyone know the opening hours for the Mail Handling Site A Wolverhampton over Christmas?.
Do they close for a Christmas break (besides the bank holidays and weekends etc)?

We recieved the form on 29th November with a return deadline of 30th December 24
I'm planning on sending it special delivery, but im concerned about meeting the deadline due to the bank holidays and how the weekends fall.

We called the number on the letter (Health Assessment Advisory) but the advsior seemed to struggle to understand us and said: "they couldn't say when to send it because that depends on royal mail" and "they didn't know the opening hours".

It's taking longer than expected to fill in due to various things including: My Severe Generalised Anxiety Disorder and Depression (historically I've always struggled even more at this time of year). my pain and fatigue, my fathers terminal cancer and my anxiety / depression medication being changed (which im still in the middle of).
I'm also very worried about the quality of my evidence.


Background:
I recieve PIP (enhanced for both). My partner is my carer and gets Carers Allowence. he used to get Income Support (as a couple) and my "Sickness elements" were paid through that, so I've never applied for ESA (old style). We have recieved ths for over 10 years.

As we have children we were recieving Child Tax Credit, we have now moved to Universal Credit via managed migration (End Sept 24).
I am on the "Health track" and have given in a sick note (i will be giving a new one soon).
At the moment my commitments are just: to check my journal, Keep them up to date and attend meetings with my "work coach - these have been 4 weekly and on the phone.
On 28/10/24 i recieved a note in my journal telling me that they were sending the UC50 form.
I recieved this on 29/11/24 - it was dated 27/11/24.

Thanks