‘Sunset Boulevard’ actress had never seen a Broadway show before she starred in one

“Sunset Boulevard” actress Grace Hodgett Young starred in a Broadway show before she ever saw one herself.

After five months of performing six days a week in the musical The Post called “Broadway’s most exhilarating show in years,” she finally got to experience what it’s like to be in the audience on the Great White Way.

“I know, it’s crazy . . . I couldn’t believe I made my Broadway debut before seeing my first Broadway show,” Young, 22, told The Post.

“I saw my first, which was ‘Smash,’ last Monday.”

The native of Nottingham, England, said she was “utterly inspired” by the quintessential Big Apple moment.

“Taking a night to go to the theater is so f–king exciting,” she gushed.

Her trip to Gotham to star in the musical — where she plays the principal role of Betty Schaefer, an aspiring writer determined to make it in Hollywood — was her first time visiting New York, and America, and she was “absolutely terrified.”

“I was freaking out, I’m not gonna lie to you. . . . I didn’t know what to expect because I never really pictured that this job would take me to New York. . . . It just seemed so far-fetched,” said Young, whose first professional role was in “Sunset Boulevard” in London’s West End.

“So to be here now is insane.”

For the duration of the show, at the St. James Theatre until July 13, she’s living in Hell’s Kitchen — where the biggest thing she had to get used to was the “the constant stream of traffic” outside her window.

“I’ve asked people in the cast, and apparently the road that I can see out my window is notoriously known for bad traffic,” she said.

“Every single day, without fail, it’s just blocked with cars and people are honking their horn like there’s anywhere to go and there’s really not.”

The Post praised Young for her “strong” performance as Betty — who finds herself in a messy love triangle with fellow writer Joe Gillis, played by Tom Francis, and Norma Desmond, a seasoned Hollywood actress played by former Pussycat Doll Nicole Scherzinger.

Young was working as a waitress in a London bar called Skylight when she auditioned for a smaller role in its ensemble.

However, its director Jamie Lloyd was so impressed with her, he asked if she was available the next day to try out for Betty — which earned her a nomination for an Olivier Award, the British equivalent of a Tony.

“I said, ‘Yes,’ and I actually wasn’t [free] because I had a shift at the bar,” she said, laughing.

The night before the audition, she had to learn two of the show’s songs, written by legendary composer Andrew Lloyd Webber, and the morning of “they taught me some more songs at about 11 a.m. and then I had to be back at 2 and do them,” she recalled.

Young got the call she’d landed the part while on the bus commuting home from a 12-hour shift at the watering hole, where she was about to get promoted to bartender.

“I was at the phase where they were training me to be on the bar, but after I got that call, I literally called my boss and was like, ‘I got a job. I’ve got to go.’”