Disclosure of Road Traffic Offence for my PSW

Hi Guys,

Can someone please advice me about non disclosure of traffic offence in a previous application of Leave to Remain. I got an extension for my student visa last year without disclosing the traffic offence in my application form, which was a mistake on my side.
The problem now is that, I want to transfer my satus to PSW later in the month of December and I'm planning to disclose this offence in my new application. I have an in-person appointment in one of the HM center, but I'm scared they might refuse my application on the grounds of 320(7B) i.e. failing to disclose a criminal conviction in a previous leave to enter, remain or visa application.

I need help please!!