With regards to NI - you do realise that you can get credits while you have children under 12? This should happen automatically if your child benefit is in your name. If you are trying to pay to make up previous gaps there are other rules, I don't think you have to be in current employment to do so.
Speak to an accountant - my brother in law is self employed and my sister is about to start working for him. He was advised to set up as a limited company and give sister a wage, presumably as was most tax efficient. Sister is already eating into the profit buying lots of matching officey stuff!
Background: Dp works 16 hours in a shop. Last year he set up his own small business but still works in the shop (making sure its viable before quitting). I'm a SAHM.
Dp is the only employee in the business however i do all the accounts (not qualified for this, just learning as i go) I take all phone calls to arrange appointments and drive dp about as he cannot drive. So most days i take dp to a job then either wait in the car if its a small job or go home/do housework until he is done, then i'll pick him up. Kids are in school but dd3 just mornings, but i can take her with me on the afternoons and find a play park nearby until he is done.
So to the question: If i wanted to be employed by him but not get a wage what is the best way to do this? All money goes into the business or housekeeping money, Dp does not keep the money. We receive working tax credits and child tax credits, also some HB ans Council tax benefit. Would they expect me to be getting a wage if i claimed i was working say 10 hours a week? How would that affect us and can i say i'm a partner for the business or should dp "employ" me.
BTW the reason I want to do this is so i can pay some NI conts as i'm slightly behind as i worked part-time for quite a while before dcs.
Hope all this makes sense as i'm not very good at explaining stuff.