Ok, the Daughter is asking, as she has to file US taxes this year on US income. She won't owe anything, and will get all her withholding back. She expects to have no future US income.
BUT, she now has UK income. It's not much. For the forseeable future it won't be a lot - certainly nowhere near the limit of the foreign earned income exclustion for decades, I would think, if ever. She has no other income.
So, the tax bit. Given that, since she has to report it to the IRS, is there a reason she would not want to just exclude the income, rather than trying to sort out Foreign Tax Credits on it?