Car Tax Query

[Jb2020]

Hi there,
I'm not sure if this is the right forum to post a question like this but any help would be greatly appreciated!
My car is due to be taxed this week but I cannot find the V11 letter with the reference number needed to register online. I discovered that if I didn't have this letter I could use my log book instead. However, I have recently moved and have boxes of paper work stored in the garage, yet to be unpacked. I don't have time what with work etc to go through the boxes between now and Tuesday (the tax date deadline). I then saw I could go to the post office and purchase a new log book for £25 (which I can easily do on my lunch break).
My question is therefore this: Can I buy a new log book and tax the car at the post office all in one go?
It's really stressing me out - my own fault for being so unorganised. But if anyone could answer my question is be grateful! Many thanks in advance.

[bd6759]

https://www.gov.uk/vehicle-tax