No problem! And oh, maybe I get where the confusion is. Do you think you have to do self assessment and your national insurance seperately? When you do your self assessment, it'll also figure out your national insurance contributions. It's all sort of in one thing and is actually very straightforward (waaaaay easier than US taxes, assuming your business is fairly simple). But yeah, give them a call if you need help. I do generally find them pretty helpful, it's just that freelance Americans working in the UK are not that common, so the information we need isn't always readily available.

As a complete side note just because this is something I struggled with, as a freelancer in the UK, you'll need to get a document as proof that you're paying national insurance, which you then send in to the IRS with your US tax return so that you're not charged self employment tax in the US (because for some reason we can be exempt from paying income tax automatically, but not the self employment tax...). Unfortunately, I don't remember exactly who you have to call to get that because I remember having to make a few calls around to ge the right person. I might try and find the number later...