Despite being named in this year's Six Nations squad, the 21-year-old Harlequins prop was not fielded during the tournament.
However, he has been named in Stuart Lancaster's starting lineup for the match in Durban this weekend.
"I'm buzzing," he said. "It's still sinking in - hopefully it will sink in by tonight, then I can properly get ready for Saturday. I'm really excited.
"You want to test yourself against the best and South African front rows are another step up. It should be good."
Saturday's match against the former World Cup winners marks the start of a three-Test tour for England.