Saints are hoping to build on last season’s efforts in Europe, having not won a continental trophy since the 2013-14 Challenge Cup.
“We just want to make memories and see if we can go even further,” added Langdon.
“Castres coming here, big French pack. Physically, we weren’t there first half (against Gloucester), it’s a big test next week to right some wrongs.”
With seven rounds of matches having been played, Northampton are eighth in the Premiership and have to close a 10-point gap to the play-off places to have a chance of retaining the title they won for the first time in a decade last season.
One consolation for Saints was the sight of England scrum-half Alex Mitchell making a first appearance of the season as he came off the bench following a neck injury.
Langdon added: “It’s been a tough time for Mitch, he picked up this injury, there was a bit of uncertainty on how long he was going to be out for, we knew he’d be back but we didn’t know when.
“When he came on it gave us a big boost. He’s obviously excited to be back and brought a lot of tempo to our play in the second half.”
