So long USA – Hullo UK as ASHTON KUTCHER & MILA KUNIS escape the States – and are moving to London!

Sources say the “Two and a Half Men” star, 35, and Mila, 29, fell in love with England’s cultured lifestyle after spending quality time there while Mila has been filming a movie.

“Mila is thrilled to leave Los Angeles because she doesn’t think it’s big enough for her, Ashton and (his ex-wife) Demi Moore,” said an insider.

“She’s also been pushing Ashton to cool his friend­ship with Demi’s daughters, and she’s sure living across the pond will take care of that.”

Ashton has been jetting into London regularly to visit Mila, and they seem to have settled into a blissful domestic routine.

“They enjoy afternoon walks through Hampstead Heath and Sunday supper at a pub,” said the insider. “They spend most nights in, hosting dinner parties or watching movies.”

As The ENQUIRER has reported, Ashton struck up a bromance with British billionaire Richard Branson after plunking down $250,000 to reserve a spot on Branson’s Virgin Galactic suborbital spacecraft.

Through Branson, the “That ’70s Show” lovers have also befriend­ed Princess Beatrice, the 24-year-old daughter of Prince Andrew and Sarah Ferguson.

“Princess Bea has promised to introduce them to London social life,” said the insider.

“Ashton will commute during breaks in filming and he’s planning to sell his home in L.A. after his contract ends on ‘Men.’ But he and Mila are already house hunting in London. They’re excited to start their English adventure!”