The young Magpies face the League Two outfit at Valley Parade in their opening Northern Section Group H clash, with United's second-string also set to face Rotherham United, who won the competition in 2022, and Mansfield Town.
Heffernan, who joined the Magpies last summer following his departure from AC Milan, is relishing the encounter against EFL opposition as well as the prospect of featuring in front of a sizeable crowd.
The teenage centre-back told newcastleunited.com: "These games are probably the ones that we are tested in the most during the season. They are big as you are playing against first-team players and men so it's a step up from the Premier League 2.
"Everyone looks forward to those games as there's a lot of people watching and it's good to put your name out there and show how good you are as a player.
"Everybody wants to play at big stadiums in front of fans. It's something we got the opportunity to do at St. James' Park a couple of times last season and it's always nice to get that experience of playing in a massive ground.
"Coming up against established strikers and playing against men who've played throughout the leagues is a good test compared to players at under-21 level who may not have as much experience."
Heffernan, a representative of Republic of Ireland at under-19 level, was one of a handful of youngsters who travelled to Germany and Japan this summer for the Magpies' pre-season preparations for the 2024/25 season.
The Cork-born defender, who made his United first-team debut during a 4-1 win against Urawa Red Diamonds in July, is keen to build on his experiences with Eddie Howe's side in the opening stages of the current campaign.
"You're playing with some of the best players in the world," Heffernan added. "You don't get the opportunity to train with them nearly everyday but when you're out on those trips, you're in and amongst the group and feel like you're a part of it.
"The standard is really high and you learn so much. You can pick up so much in one week and you always have to be switched on to try and take in as much information as you can to then be able to apply that whether you're playing for the under-21s.
"I watched all of the centre-backs in the first-team, especially Fabian (Schär), (Emil) Krafth and Dan Burn. Even if you can take one or two things from each of them, it's amazing as you can learn a lot."
Tickets for Newcastle United Under-21s' EFL Trophy clash away at Bradford City on Tuesday, 3rd September can be purchased here. Please note anyone under the age of 14 must be accompanied by an adult at all times.
On the day of the game, there are large QR codes outside the away turnstiles on Midland Road (E7-E12 Away turnstiles) for any supporters who wish to purchase a ticket on the day. It is online only and there will be no cash/card turnstiles.
