When renewing your PSV driving licence, I advise to bring with you, as well as the mandatory items, the "items which may be requested" i.e. passport, and NDLS diving history, because they will be requested.
NDLS driving history is availabe by email from NDLS in approximately 10 days.
If your driving licence history has penalty points you will be required to get a letter from your insurance company, on their headed paper, stating that they are aware of the points, and to get this letter you have to email them your NDLS driving history, and they will email you the required letter by return.
I was in there this morning, and contrary to an NTA Google seach the Carriage Office is not open 9-17, but from 9.30-12.45, and 14.00-16.30. Luckily I had my passport on my phone, and was able to email it to her there and then. I had my printed NDLS history with me, as well as on my phone, and I then emailed my NDLS history to my insurance who will email the required awareness letter, which Louise in the Carriage Office said is acceptable to be sent to her by post.