The 19-year-old former kitchen porter, who had yet to pass his driving test when he won the esports title for the Mercedes team last year but has done so now, became the sport's inaugural virtual champion in 2017.
FF1600website.com said Leigh, who will race on Saturday and Sunday, had already done three days of testing to prepare for his debut with the Kevin Mills Racing team.
"He was fast straight away," it quoted team boss Kevin Mills as saying. "He wasn't too different to my other two drivers really. His laptimes were fairly similar. He'll go well."
Leigh shed more than 20kg last year as he transformed from a chubby teen to a lean, professional gamer, working out at the Mercedes team factory with a Formula One trainer.
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(Reporting by Alan Baldwin, editing by Pritha Sarkar)
