Option 1: File in the US as a US resident for the full year, and take various exemptions, deductions, and credits to offset the US tax arising from the UK income.
Option 2: File as a dual status alien on form 1040NR and pay tax only on your US source income.
In any event, these returns are difficult to prepare and you should probably seek expert tax preparation services for your final year of US residency.
IRS Circular 230 Disclosure: To ensure compliance with requirements imposed by the U.S. Internal Revenue Service, we inform you that any tax advice contained in this communication (including any attachments) was not intended or written to be used, and cannot be used, by any taxpayer for the purpose of (1) avoiding tax-related penalties under the U.S. Internal Revenue Code or (2) promoting, marketing or recommending to another party any tax-related matters addressed herein.