The Glovers head to Wilshire after a run of five straight defeats whilst the Robins still have an outside chance of reaching the play-offs.
Taking charge of his second match since being appointed until the end of the campaign, Marmon is comfortable going into the fixture as underdogs.
“They’re pushing for promotion but I hope they underestimate us,” he told iFollow Glovers. “We’re trying to go there and nick something and we haven’t got anything to lose.
“Obviously, we need the points but because they’re in good form not many people expect something.
“Their three strikers are very, very quick and we’re aware of that but we’re just focusing on ourselves at the moment and concentrating on getting our game better, defending better and going forward better.”
The 59-year-old oversaw his first game on the touchline last weekend as the green and whites fell to a 3-1 defeat at home to Newport County.
Despite the loss, Marmon feels there are positives to take into the trip to the County Ground on Saturday.
“A lot of pepole saw in the game last week that we kept the ball well for 60 minutes and after the goal, we conceded the second goal quickly which broke our morale a little bit.
“The boys fought back and made it 1-2 and we were pushing for a second but got caught on the break, so we have to be aware of that because Swindon do break very well.
“I thought our last game was quite good for 60 minutes and if we can keep building on that I think we’ll get the points we require.”