This is about how you calculate your 'worked hours' in order to assess your eligibility for the 30 funded hours of childcare. *
I realise it’s not much on an answer, and a pain in the bum to do, but I think you’re going to have to call the helpline.
The worked hours in calculated as an equivalent number of hours at minimum wage rate, based on your actual income. As you’re self employed, and the income varies across the year, you need to find out if they calculate this based on your annual income, averaged across the year, or on a strictly week-to-week basis. Logic suggests the former, but it’s rarely safe to assume HMRC will follow a layperson's logic.
Also, there is an annual income ceiling beyond which you wouldn’t be entitled to 30 hours. Obviously you can’t calculate your annual income before the end of your accounting year, so I honestly don’t know how they’d work it out. Possibly they use last year’s figures with some notional adjustment? Again, best to get the answer straight from the horse's mouth, but it can mean a lengthy time on hold.
I think the number to call is 0300 123 4097.
*incidentally, I refuse to call it "free" childcare; it is being subsidised by childcare providers.