Hartpury were only founded in 2020 and now sit top of the Hellenic Football League Premier Division.
Their squad can range from 16-year-old BTec and A-level pupils to a 25-year-old who is studying for a masters degree.
“It’s been brilliant. It’s a fantastic environment,” said Longworth.
“We got to the last 32 two years in a row. This year, we just wanted to go one better.
“In the last round we realised this is huge. People are starting to take notice and it is what the lads deserve.”
Whitstable, who host the first leg, play in the ninth-tier Southern Counties East Football League, the same division as Erith & Belvedere who Hartpury beat 2-1 in the quarter-finals.
About 3,000 tickets have been sold for the first leg in Kent, leaving the visitors relishing playing in front of a large crowd, before they host the return on 6 April.
“The most we have ever played against is probably 600-700 in the previous round,” said Longworth.
“It will probably be one of the biggest games of these guys’ lives, and for some of them the best opportunity they are ever going to have.”
