There are competitive London to Chicago flights available with Icelandair. Return tickets with a layover in Reykjavik are available for £280 in Q1 of 2023. This is for a roundtrip ticket inclusive of all taxes and fees, onboard meals, and a handbag. There is no checked luggage in the base fare only available for an extra fee.
Booking sample of cheap Icelandair flights from the UK to Chicago for £280! As per the above link, you would fly from London Gatwick to this city in the USA on the 5th of March returning from America back to the United Kingdom on the 19th of March 2023.
