Help! Government gateway and self assessment advice

Hi - hope you can help. I'm trying to set up as a sole trader as I expect to transition to working for myself in a couple of months. I need to sign up for self assessment, but the question I have is this: do I use my existing government gateway ID that is in place for all my existing tax records, or do I need to create a second, separate ID as a sole trader? It's a really simple Q with a really simple answer but I've been on hold to the HMRC phoneline this morning for two hours before being cut off twice, the 'online advisor' is just a chatbot that is of no help, and the online guides don't answer my question either...

Hi,

If you already have a self assessment reference you will use the same number. You will use this to register for class 2 national insurance also.

Thank you.