Aidy Boothroyd's side remain in third place after sitting out the weekend action and are one place and seven points behind their hosts.
They will travel in high spirits after the excellent win at Aldershot while Gillingham, despite remaining in pole position for promotion, have taken only two points from their last five home games.
One of those was rescued by new loan signing Cody McDonald against York on Saturday after which manager Martin Allen said: "Well done for Cody and well done for the second half performance but I think everyone knows we need more and we can do better and we will do better.
"I am already looking forward to Tuesday night."
Source: Cobblers Mad