05/15/2009 at 07:00 PM EDT
Joss Stone is trading in her soulful singing voice for a German accent.
Starting Sunday, the British musician plays Anne of Cleves – the fourth wife of England's King Henry VIII – in the season's last two episodes of The Tudors
"I enjoyed wearing the dresses," Stone tells PEOPLE of her 16th-century wardrobe. "But the thing about Anne of Cleves is, she was not supposed to be attractive. Anne, let's be honest, was described as quite frumpy and ugly. But hey, I did it! I did my best! They had no problem making me ugly. Lots of makeup!"
Modesty aside, Stone, 22, still turns heads in the Showtime drama, which she filmed in Ireland last year.
"It was cold, so in our off time we went to a lot of comedy clubs. The Irish are funny f---ers – they make me laugh," says Stone, who adds that she was "looked after" by her dashing castmates including Henry Cavill (who plays Charles Brandon), Andrew McNair (Thomas Seymour), James Frain (Thomas Cromwell), and the king himself, series star Jonathan Rhys Meyers.
"Johnny was lovely," says Stone, who appears in the May 17 and 24 episodes. "A great guy, very cool. He's a beautiful spirit and a beautiful man."
Next up for the soul singer: a summer tour and, she hopes, more acting roles, including a return to The Tudors
for the period drama's fourth season. "The sky's the limit," she says. "I don’t really know what I'm good at yet in this field. But there's nothing that I won't do or try."
For more on Joss Stone, including her favorite TV theme songs, pick up the new issue of PEOPLE, on stands now.