NI contributions when both employed and self employed

I’m employed (currently on mat leave) and pay class 1 NI contributions, however have recently started my own business too. I’m a bit confused how much (if any) NI I will have to pay in my self employment. I don’t expect to make a profit this first year so am I right in assuming I won’t pay NI? And if not, should I still make voluntary contributions as I am already contributing through my employment. Also, when I am making a profit (less than £6k) would I pay class 4 contributions on this aswell as my class 1 contributions or not? I’m just a little confused by the advice online and want to make sure I’m setting enough aside when it comes to self assessment.

Hi
Please look here Self-employed National Insurance rates re self employed national insurance and we also have webinars for self employed sole traders that should  be useful HMRC email updates, videos and webinars if you’re self-employed