I am a Wisconsin resident/US citizen, but I moved to the UK in Jan 2019. How do I enter this info on my return?

In the My Info section, there are two places to indicate that you reside overseas.  First, in your Personal Info Summary, when TurboTax asks Tell us the state(s) you lived in, you select Foreign or U.S. Possession.  Then, under Mailing Address, in the dropdown for Type of mailing address, select Foreign country.  Enter your phone number in the box provided at the bottom of that screen.

If you have a W-2 form with your foreign address, note that on the W-2 entry screen, for box f Employee's Address there is an Other "button".  Make that choice, and then select the Foreign Address button to enter a foreign address.

Also, note that as a U.S. citizen, the rules for filing income tax returns and paying estimated tax are generally the same whether you are in the United States or abroad. Your worldwide income is subject to U.S. income tax, regardless of where you reside.

But, if you had income from foreign sources and were either a bona fide resident of a foreign country or were physically present there for most of the year, you probably qualify to exclude some or all of your foreign income from taxation by the U.S.  Even if you don't meet those tests for foreign income exclusion, you get a credit for foreign taxes paid on our income.

See the IRS website at this link for more information, and other links to the foreign income exclusion and foreign tax credit.